As filed with the Securities and Exchange Commission on April 28, 2005

Registration No. 333-          

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

SOUTHERN PERU COPPER CORPORATION
(Exact name of registrant as specified in its charter)

2575 East Camelback Road
Phoenix, Arizona 85016
(602) 977-6595
(Address, including zip code, and telephone number, including area code, of registrant's principal executive offices)

Armando Ortega Gómez
Secretary
Southern Peru Copper Corporation
2575 East Camelback Road
Phoenix, Arizona 85016
(602) 977-6595
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:
Michael L. Fitzgerald, Esq.
Robert B. Williams, Esq.
Milbank, Tweed, Hadley & McCloy LLP
One Chase Manhattan Plaza
New York, New York 10005

        Approximate date of commencement of proposed sale to the public: From time to time on or after the effective date of this Registration Statement.

        If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. o

        If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, please check the following box. ý

        If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

        If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

        If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. o

CALCULATION OF REGISTRATION FEE

(1)

Estimated solely for the purpose of calculating the amount of the registration fee in accordance with Rule 457(c) of the Securities Act of 1933, as amended, based on the average of the high and low sale prices of the Registrant's common stock as reported on the New York Stock Exchange on April 27, 2005.

(2)

Includes up to 1,573,387 shares that the underwriters have the option to purchase to cover over-allotments, if any.

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

        This registration statement relates to common stock of Southern Peru Copper Corporation that may be offered from time to time by our selling stockholders named herein. This registration statement includes a base prospectus relating to the sale by our selling stockholders in one or more offerings of up to 22,551,884 shares of our common stock. In any offering, the base prospectus will be accompanied by a prospectus supplement. This registration statement also includes an illustrative form of prospectus supplement in preliminary form setting forth the terms of an offering by our selling stockholders.

The information in this prospectus supplement is not complete and may be changed. The selling stockholders may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus supplement is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED APRIL 28, 2005

PROSPECTUS SUPPLEMENT

              Shares

Southern Peru Copper Corporation

Common Stock

$         per share

        The selling stockholders named in this prospectus supplement are selling            shares of our common stock. We will not receive any of the proceeds from the sale of the shares by the selling stockholders.

        Our common stock is listed on the New York Stock Exchange and the Lima Stock Exchange under the symbol "PCU". The last reported sale price of our common stock on the New York Stock Exchange on April    , 2005, was US$    per share.

        Investing in our common stock involves risk. See "Risk Factors" beginning on page S-10.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the related prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

        The underwriters may also purchase up to            additional shares of common stock from the selling stockholders, at the public offering price less the underwriting discounts and commissions, within 30 days from the date of this prospectus supplement. The underwriters may exercise this option to cover over-allotments, if any. If the underwriters exercise the option in full, the total underwriting discounts and commissions will be US$        , and the total proceeds to the selling stockholders will be US$        .

        The underwriters expect to deliver the shares on or about                  , 2005.

                        , 2005

        You should rely only on the information contained in or incorporated by reference in this prospectus supplement and the accompanying prospectus. We have not, and the underwriters and the selling stockholders have not, authorized anyone to provide you with information that is different. The selling stockholders are offering to sell shares of common stock only in jurisdictions where offers and sales are permitted. The information contained in this prospectus supplement is accurate only as of the date of this prospectus supplement regardless of the time of delivery of this prospectus supplement or any sale of our common stock.

TABLE OF CONTENTS

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Financial and Other Information

        Throughout this prospectus supplement, unless the context otherwise requires, the terms "we," "us" and "the Company" refer to Southern Peru Copper Corporation and its consolidated subsidiaries, including our recently acquired Minera México subsidiary and its consolidated subsidiaries; the terms "Southern Peru Copper Corporation" and "SPCC" refer to Southern Peru Copper Corporation and its subsidiaries, excluding Minera México and its consolidated subsidiaries; the term "Minera México" refers to our subsidiary, Minera México, S.A. de C.V., and its consolidated subsidiaries; and "selling stockholders" refers to the selling stockholders identified under "Principal and Selling Stockholders."

        Many of the terms used in this prospectus supplement are defined in the glossary of mining terms, beginning on page A-1.

Financial Information

        Our financial statements and other financial information included in this prospectus supplement reflect the combined accounts of Southern Peru Copper Corporation and Minera México. Effective April 1, 2005, SPCC acquired substantially all of the outstanding common stock of Minera México. The acquisition was accounted for in a manner similar to a pooling of interests as it involved the reorganization of entities under common control. Under applicable accounting requirements, the financial statements of SPCC and Minera México are combined on a historical cost basis for all the periods presented since they were under common control during all of the periods presented. The combined financial results may not be indicative of the results of operations that actually would have been achieved had the acquisition of Minera México taken place at the beginning of the periods presented and do not purport to be indicative of future results.

        This prospectus supplement includes Audited Combined Financial Statements as of December 31, 2004, and for each of the years in the three-year period ended December 31, 2004. This prospectus supplement also includes certain combined financial information as of and for the years ended December 31, 2000 and 2001. The 2000 and 2001 combined financial information is unaudited and has been derived from audited stand-alone financial statements of SPCC and Minera México. Management has prepared the 2000 and 2001 combined financial information on a basis believed to be consistent with the basis on which the Audited Combined Financial Statements have been prepared.

Incorporation by Reference

        We incorporate by reference certain information into the prospectus attached to this prospectus supplement. See "Where You Can Find More Information" in the attached prospectus. Information in this prospectus supplement and the attached prospectus supersedes information incorporated by reference that was filed with the Securities and Exchange Commission, or the SEC, prior to the date of this prospectus supplement.

        The prospectus of which this prospectus supplement forms a part incorporates by reference our annual report on Form 10-K for 2004. Except as otherwise expressly described therein, the information included in our annual report on Form 10-K, including the financial statements and other financial and statistical data included therein, relates to SPCC prior to its acquisition of Minera México.

Reserves Information

        Our mineral reserves are estimates based on a number of assumptions, including production costs and metals prices. Unless otherwise stated, reserves estimates in this prospectus supplement are based on three-year average metal prices as of December 31, 2004. We refer to three-year average metal prices as "current average prices." For SPCC, commencing in 2003, we have used reserves estimates based on current average prices to determine the amount of mine stripping that is capitalized, units of

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production amortization of capitalized mine stripping and amortization of intangible assets. In calculating such items in the case of our Minera México subsidiary and for periods prior to 2003 for SPCC, we used price assumptions based on metals prices which are intended to approximate average prices over the long term. We also use these longer-term metals price assumptions in developing our mine plans. For a further discussion regarding how we calculate our reserves, see "Business—Reserves."

Currency Information

        Unless stated otherwise, references herein to "U.S. dollars," "dollars," "US$" or "$" are to United States dollars; references to "S/," "nuevo sol" or "nuevos soles" are to Peruvian nuevos soles; and references to "peso," "pesos" or "Ps." are to Mexican pesos.

Industry and Market Data

        This prospectus supplement includes market share and industry data and forecasts that we obtained from or are based upon internal company surveys, market research, consultant surveys, publicly available information and industry publications and surveys. Industry publications and surveys, consultant surveys and forecasts generally state that the information contained therein has been obtained from sources believed to be reliable, but we cannot assure you as to the accuracy and completeness of the information. We have not independently verified any of the information from third-party sources nor have we ascertained the underlying economic assumptions relied upon therein. We do not guarantee the accuracy or completeness of this information. Similarly, internal company surveys, industry forecasts and market research, which we believe to be reliable based upon management's knowledge of the industry, have not been verified by any independent sources.

Other Information

        Throughout this prospectus supplement, unless otherwise noted, all tonnages are in metric tons. To convert to short tons, multiply by 1.102. All ounces are troy ounces. All distances are in kilometers. To convert to miles, multiply by 0.621. To convert hectares to acres, multiply by 2.47.

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SUMMARY

        You should read this entire prospectus supplement and the accompanying prospectus, including information incorporated by reference, before making an investment in our common stock. You should also carefully consider the information set forth under "Risk Factors." In addition, certain statements include forward-looking information that involves risks and uncertainties. See "Forward-Looking Statements."

Overview

        We are the world's largest publicly traded copper company as measured by reserves. Based on 2004 sales, we are the world's fifth largest copper mining company, and the third largest copper smelting and fifth largest copper refining company. We believe that we are also among the world's largest producers of molybdenum, silver and zinc.

        All of our mining operations are located in Peru and Mexico and we conduct exploration activities in Peru, Mexico and Chile. We own and operate the following mines and metallurgical complexes:

•

Four Open-Pit Copper Mines  



•

Our Cuajone and Toquepala mines, located in southern Peru, produced 397,366 tons of copper in 2004 (194,389 tons at Cuajone and 202,977 tons at Toquepala).



•

Our Cananea mine, located in northern Mexico, produced 173,428 tons of copper in 2004. We believe Cananea is among the world's largest copper mines in terms of reserves, and has the longest remaining mine life of any major open-pit copper mine in the world based on current production levels.



•

Our La Caridad mine, located in northern Mexico, produced 132,160 tons of copper in 2004.



•

Three Metallurgical Processing Complexes  



•

Our Ilo complex, located in southern Peru, includes the world's sixth largest copper smelter and eighth largest copper refinery, a precious metal refinery and a sulfuric acid plant. We are currently modernizing the Ilo smelter facility with Isasmelt technology to reduce emissions.



•

Our La Caridad complex, located in northern Mexico, is a modern metallurgical facility that includes what we believe is one of the world's largest copper smelters and one of the largest copper refineries, a precious metal refinery, a copper rod manufacturing plant and a sulfuric acid plant.



•

Our San Luis Potosí complex, located in central Mexico, includes an electrolytic zinc refinery, a copper smelter and a sulfuric acid plant.



•

Underground Mines and Related Processing Facilities  



•

We own and operate five underground mines that produce various metals such as zinc, copper, silver and gold, as well as a coal mine and related production facilities, all of which are located in Mexico.

        On April 1, 2005, we acquired Minera México from Americas Mining Corporation, or AMC, a subsidiary of Grupo México, S.A. de C.V., our controlling stockholder. On a stand-alone basis, Minera México, which owns the Cananea and La Caridad mines, among other assets, is the largest mining company in Mexico and the eleventh largest copper producer in the world. On April 1, 2005, we exchanged 67,207,640 newly issued shares of our common stock for the outstanding shares of Minera México, and Minera México became our 99%-owned subsidiary. Upon completion of the merger, Grupo México increased its indirect beneficial ownership of our capital stock from approximately 54.2% to approximately 75.1%.

S-1

        For the year ended December 31, 2004, after giving effect to our acquisition of Minera México, we had net sales of US$3,097 million and net earnings of US$982 million. We produced 718,007 tons of copper, 14,373 tons of molybdenum, 18.5 million ounces of silver and 133,778 tons of zinc in 2004, approximately 50% of which was sold outside of Latin America. As of December 31, 2004, we had proven and probable reserves of approximately 44.9 million tons of copper.

Competitive Strengths

        Second largest copper reserves in the world.    We have an estimated 44.9 million tons of proven and probable copper reserves, the second largest copper reserves in the world and the largest copper reserves of any publicly-traded company.

        Highly integrated copper production.    We are a highly integrated producer of copper which enables us to maintain high smelter utilization, achieve pricing premiums through value-added copper products and reduce our reliance on third parties for treatment and refinery services. For example, our Cananea and La Caridad mines provide a stable and secure source of copper concentrate for our La Caridad complex, our Cuajone and Toquepala mines supply our Ilo complex and our underground mines provide zinc and copper concentrate for our San Luis Potosí complex. Our integrated operations enable us to have significant economies of scale with reduced costs and earnings volatility.

        A portfolio of low-cost operations.    Our copper mines are well positioned from a cost perspective. In addition to our integrated operations, we believe we benefit from other advantages that contribute to making us a low-cost producer of copper and other metals. These include the relatively high quality of our reserves and the proximity of many of our operations to each other.

        Diversified mix of operations.    We operate four copper mines, with no one mine contributing more than 28% of our total mine production. We also operate three metallurgical complexes. We believe this diversity of operations reduces the impact of a major mine failure or labor disruptions at any one operation. We offer a diverse product mix that includes molybdenum, a byproduct of our copper mining operations, as well as other byproduct metals, such as zinc and silver. We believe we are one of the world's largest producers of molybdenum. Further, our operations and reserves are balanced between Peru and Mexico, countries with a tradition of mining and well-established mining laws.

        Significant organic growth prospects that can be financed with internal funds.    We have identified a number of potential development projects that we believe can be implemented to increase our future production capacity without major investments. These development projects, which include several brownfield projects that together could increase our production capacity by an estimated 88,000 tons of copper per year, can be financed by internally generated funds and can be implemented within two to three years. We also have identified other potential brownfield and greenfield projects at our properties in Peru and Mexico and are currently conducting exploration activities in Peru, Mexico and Chile.

        Management team with a track record of success over our long operating history.    Our senior managers have an average of 20 years of experience with our Company or its predecessors. Our senior managers have successfully led the Company in varied economic conditions and have a track record of improving operating efficiency and reducing costs.

Business Strategies

        Our objective is to increase stockholder value through earnings and cash flow growth in varied market conditions. We seek to achieve this objective by focusing on the following strategies:

        Growing and expanding our operations.    We intend to further realize the potential of our existing operations by expanding our production capacity and reserves, as well as exploring and developing promising mineral deposits. We believe that our existing operations have significant growth potential

S-2

that can be financed principally through internally generated cash flows. We also intend to supplement internal growth by selectively pursuing value-enhancing acquisition opportunities.

        Continuing our focus on copper.    We are primarily a copper producer, with approximately 68.1% of our 2004 revenues derived from copper production. We intend to continue to focus principally on the production of copper. Our earnings and cash flows are highly sensitive to movements in the price of copper, and we estimate that a US$0.01 per pound increase in the price of copper would generate approximately US$15.6 million of additional operating income based on our 2004 total production.

        Improving the cost position of our operations.    We are focused on improving our cost structure in order to maintain our profitability throughout the commodity price cycle and to generate cash flow to fund attractive investment opportunities. We seek to lower costs by (i) improving economies of scale through production expansions, (ii) investing selectively in new equipment and advanced production technologies, such as SX/EW, and (iii) fully utilizing our metallurgical facilities to capture processing margins and premiums.

        Maintaining a relatively conservative capital structure.    As of December 31, 2004, we had a cash balance of US$756 million and total debt of US$1.33 billion, giving us a net debt position of US$574 million and a ratio of net debt to net debt plus shareholders' equity of 0.17. We seek to maintain a relatively conservative level of financial leverage with the goal of enabling us to minimize our borrowing costs, to be opportunistic regarding growth projects and strategic investments and acquisitions and to reduce financial risks during market downturns.

        Dividends.    We have distributed a significant amount of our net income as dividends since 1996. We anticipate paying significant amounts of dividends for the immediately foreseeable future, although we cannot assure you that this dividend practice will be maintained.

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Copper Market Conditions

        Copper is a fundamental material in the world's infrastructure. Copper has unique chemical and physical properties, including high electrical conductivity and resistance to corrosion, as well as excellent malleability and ductility, that have made it a superior material for use in the electrical energy, telecommunications, building construction, transportation and industrial machinery businesses. Wire and cable products, used principally as energy cable, building wire and magnet wire, account for as much as 71% of copper consumption. Copper is also an important metal in non-electrical applications such as plumbing, roofing and, when alloyed with zinc to form brass, in many industrial and consumer applications. The building and construction industry accounts for approximately 37% of worldwide copper usage. Worldwide copper sales in 2004 were estimated to be approximately US$48 billion based on 2004 worldwide copper sales of 16.9 million tons and the average copper price per pound in 2004 of US$1.29.

        Historically, the price of copper has been both volatile and cyclical, a reflection of current and expected economic conditions and the supply of and demand for copper.

        During the 1980s and 1990s, copper prices averaged, on an annual basis, approximately US$0.84 per pound and US$1.01 per pound, respectively. The price of copper has increased considerably over the past few years since its 15-year low reached in November 2001, particularly since March 2003 when significant appreciation of the metal commenced. In 2004, the average copper price of US$1.29 per pound was almost US$0.50 higher than the previous year's average. We believe factors contributing to the current strength of copper prices include:

•

Reduced supply and low inventory levels.  Reduction in new mine development, declining grades at existing mines and discipline among existing producers in not expanding production have all contributed to a current supply deficit. This has been aided by the significant restructuring and consolidation in the industry over the past few years. Current inventories of copper held by producers and commodity exchanges are at historically low levels. When copper inventories are low, higher copper prices generally result.



•

Increased demand, especially from China.  Increases in worldwide industrial production as well as increased use of copper in developing countries have led to recent increases in demand for copper. China's growth in copper consumption, which accounted for approximately 40% of the increase in global market consumption of copper in 2004, has been a significant contributor to demand. Demand has also benefited from a recovery in the U.S. manufacturing sector. As producers' and commodities exchanges' inventories have decreased and industrial production and consumer confidence have increased, end users have increased their business inventories of copper as they have realized the need to have copper available, particularly on short notice.



•

Weakening U.S. dollar.  There has been a strong inverse correlation over time between copper prices and U.S. dollar exchange rates. Approximately 92% of copper production occurs in regions where the local currency is not the U.S. dollar. Production economics for producers and the impact of raw materials costs on consumers in these regions change with movements in the exchange rate of the U.S. dollar against these regions' currencies. The current weakness of the U.S. dollar has had a significant upward impact on the price of copper in U.S. dollars.

        These factors, which are all interdependent and impact prices to varying degrees, are reflected in the current market price of copper. Changes to any one of these factors will impact prices in the future.

Corporate Information

        We were incorporated in Delaware in 1952. Our corporate offices are located at 2575 East Camelback Road, Suite 500, Phoenix, Arizona 85016 and our telephone number is (602) 977-6595. Our website is www.southernperu.com. The information on our website is not part of this prospectus supplement.

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The Offering

        Unless otherwise noted, the information in this prospectus supplement assumes the underwriters have not exercised their over-allotment option.

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Summary Combined Financial Information

        The following tables present our summary combined financial information and other data for the years indicated. These tables should be read in conjunction with the Audited Combined Financial Statements and the notes thereto included elsewhere in this prospectus supplement and are qualified in their entirety by the information contained therein. Our Audited Combined Financial Statements and the financial information in the tables below reflect our April 1, 2005 acquisition of Minera México as a combination of businesses under common control, on a historical basis in a manner similar to a pooling of interests, reflecting the financial condition and results of operations for SPCC and Minera México on a combined basis. See "Financial and Other Information—Financial Information."

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(1)

Financial information as of and for the years ended December 31, 2000 and 2001 is unaudited.

(2)

EBITDA is net earnings, plus: cumulative effect of change in accounting principle; minority interest; income taxes; interest expense, interest income; and depreciation, amortization and depletion, minus interest capitalized. EBITDA is used as a measure of performance by our management and is not a measure of performance under generally accepted accounting principles, or GAAP. We present EBITDA because we believe it provides management and investors with useful information by which to measure our performance. EBITDA should not be construed as an alternative to (a) net income as an indicator of our operating performance or (b) cash flow from our operating activities as a measure of liquidity. EBITDA also does not represent funds available for dividends, reinvestment or other discretionary uses. Because not all companies use identical calculations, our presentation of EBITDA may not be comparable to similarly titled measures presented by other companies.

A reconciliation between EBITDA and net earnings for each of the periods presented in the table is presented on page S-51.

(3)

On a historical basis, without giving effect to the acquisition of Minera México, SPCC's cash dividends paid per share were $0.34, $0.36, $0.36, $0.57 and $2.39 for the years ended December 31, 2000, 2001, 2002, 2003 and 2004, respectively.

(4)

Represents net sales less cost of sales, divided by net sales as a percentage.

(5)

Represents operating income divided by sales as a percentage.

(6)

Represents net earnings divided by sales as a percentage.

(7)

Represents net debt divided by net debt plus stockholders' equity.

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Summary Operating Data

        The following table sets out certain operating data underlying our combined financial and operating information for each of the years in the five-year period ended December 31, 2004.

(1)

Includes finished metal (including blister, cathode and rod) sales and payable metal in concentrate sales to third parties, less payable metal in third-party concentrate purchases. "Payable metal" refers to the content of metal contained in concentrates that is actually valued and paid for.

(2)

Operating cash costs per pound of copper produced is an overall benchmark we use and a common industry metric to measure performance. Operating cash cost is a non-GAAP measure that does not have a standardized meaning and may not be comparable to similarly titled measures provided by other companies. A reconciliation of our cash cost per pound to the cost of sales (including depreciation, amortization and depletion) as presented in the statement of earnings is presented on page S-51. We have defined operating cash cost per pound as the total production cost, including the cost of purchased copper, freight and sales expenses, administrative expenses, and treatment and refining charges, less revenues for the sale of byproducts such as molybdenum, zinc, silver, lead and gold on copper sales, divided by total pounds of copper we produced (including purchased copper). See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Overview—Operating Cash Costs."

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Summary Reserves Data

        The table below details our copper and molybdenum reserves as estimated at December 31, 2004. Pursuant to SEC guidance, the reserves information in this prospectus supplement is calculated using average metals prices over the most recent three years, unless otherwise stated. We refer to these three-year average metals prices as "current average prices." Our current average prices for copper are calculated using prices quoted by COMEX, and our current average prices for molybdenum are calculated according to Platts Metals Week. Unless otherwise stated, reserves estimates in this prospectus supplement use US$0.939 per pound for copper and US$8.425 per pound for molybdenum, both current average prices as of December 31, 2004. The current average prices for copper and molybdenum were US$0.751 and US$3.81, respectively, as of December 31, 2003 and US$0.760 and US$2.88, respectively, as of December 31, 2002.

(1)

The Cuajone, Toquepala, Cananea and La Caridad concentrator recoveries calculated for these reserves were 83.8%, 90.3%, 81.0% and 78.4%, respectively, obtained by using recovery formulas according to the different milling capacities and geo-metallurgical zones.

(2)

The Immsa Unit includes the Charcas, Santa Bárbara, San Martin, Santa Eulalia and Taxco mines. The information above does not include information for the Santa Eulalia mine as it was recently reopened.

(3)

Copper contained in ore reserves for open-pit mines is (i) the product of sulfide ore reserves and the average copper grade plus (ii) the product of in-pit leachable reserves and the average copper grade. Copper contained in ore reserves for underground mines is the product of sulfide ore reserves and the average copper grade.

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RISK FACTORS

        Before making a decision to invest in our common stock, you should read this entire prospectus supplement and the accompanying prospectus, including information incorporated by reference. You should also carefully consider each of the risk factors set forth below prior to deciding whether or not to purchase shares of our common stock.

        The following risks, and other risks and uncertainties not currently known to us or those that we deem immaterial, may also materially and adversely affect our business, results of operations and financial condition. In such an event, the trading price of our common stock could decline and you may lose all or part of your investment.

Risks Relating to Our Business Generally

Our financial performance is highly dependent on the price of copper and the other metals we produce.

        Our financial performance is significantly affected by the market prices of the metals that we produce, particularly the market prices of copper and molybdenum. Historically, prices of the metals we produce have been subject to wide fluctuations and are affected by numerous factors beyond our control, including international economic and political conditions, levels of supply and demand, the availability and costs of substitutes, inventory levels maintained by users, actions of participants in the commodities markets and currency exchange rates. In addition, the market prices of copper and certain other metals have on occasion been subject to rapid short-term changes.

        In 2004, a 60% increase in copper prices on the London Metal Exchange, or LME, and the Commodities Exchange, Inc., or COMEX, and a 206% increase in molybdenum prices, in addition to an 18% increase in our molybdenum production and sales, contributed to an increase of approximately 95% in our total sales in 2004 as compared with 2003. While the price of copper dropped to a 15-year low of US$0.61 per pound in 2001, it has since increased by approximately 145% to US$1.50 per pound as of April 14, 2005. The price of molybdenum has also recently increased significantly and is currently at historically high levels. The average annual price of molybdenum over the five-year period ended December 31, 2004 was US$6.73 per pound, with a price per pound as of April 14, 2005 of US$38.00 per pound. Over the past two years, as a result of this increase in molybdenum prices, molybdenum has become a significant contributor to our sales.

        We cannot predict whether metals prices will rise or fall in the future. A decline in metals prices and, in particular, copper or molybdenum prices, would have an adverse impact on our results of operations and financial condition, and we might, in very adverse market conditions, consider curtailing or modifying certain of our mining and processing operations.

Changes in the level of demand for our products could adversely affect our product sales.

        Our revenue is dependent on the level of industrial and consumer demand for the concentrates and refined and semi-refined metal products we sell. Changes in technology, industrial processes and consumer habits may affect the level of that demand to the extent that such changes increase or decrease the need for our metal products. Such a change in demand could impact our results of operations and financial condition.

Our actual reserves may not conform to our current estimates of our ore deposits.

        There is a degree of uncertainty attributable to the calculation of reserves. Until reserves are actually mined and processed, the quantity of ore and grades must be considered as estimates only. The proven and probable ore reserves data included in this prospectus supplement are estimates prepared by us based on evaluation methods generally used in the international mining industry. Independent engineers have not verified these reserves estimates. We may be required in the future to revise our reserves estimates based on our actual production. We cannot assure you that our actual reserves will conform to geological, metallurgical or other expectations or that the estimated volume and grade of

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ore will be recovered. Lower market prices, increased production costs, reduced recovery rates, short-term operating factors, royalty taxes and other factors may render proven and probable reserves uneconomic to exploit and may result in revisions of reserves data from time to time. Reserves data are not indicative of future results of operations. See "Business—Reserves."

Our business requires substantial capital expenditures.

        Our business is capital intensive. Specifically, the exploration and exploitation of copper and other metal reserves, mining, smelting and refining costs, the maintenance of machinery and equipment and compliance with applicable laws and regulations require substantial capital expenditures. We must continue to invest capital to maintain or to increase the amount of copper reserves that we exploit and the amount of copper and other metals we produce. We cannot assure you that we will be able to maintain our production levels or generate sufficient cash flow, or that we will have access to sufficient financing to continue our exploration, exploitation and refining activities at or above present levels.

The expected benefits of our recent acquisition of Minera México, including expected synergies, may not be realized.

        On April 1, 2005, we completed our acquisition of Minera México from AMC, a subsidiary of Grupo México, our controlling stockholder. We are now in the process of integrating two companies that previously had been affiliated but operated independently. We acquired Minera México based on a number of factors, including trends we believe may favor consolidation in the copper mining industry, potential improvement in production and our relative cost position, geographic diversification of our operations and potential operating synergies. We also considered potential negative effects in evaluating the transaction, including lower than expected mineral production from Minera México, diversion of management's attention and the risk that potential operating synergies may not be realized. We cannot assure you that the benefits we expect from the acquisition will be achieved or that potential negative effects will not be realized and adversely affect us.

Restrictive covenants in the agreements governing our indebtedness and the indebtedness of our Minera México subsidiary may restrict our ability to pursue our business strategies.

        Our financing instruments and those of our Minera México subsidiary include financial and other restrictive covenants that, among other things, limit our and Minera México's abilities to pay dividends, incur additional debt and sell assets. If either we or our Minera México subsidiary do not comply with these obligations, we could be in default under the applicable agreements which, if not addressed or waived, could require repayment of the indebtedness immediately. Minera México's new US$600 million credit facility contains limitations on its incurrence of additional debt and liens and on its ability to dispose of assets. Our Minera México subsidiary is further limited by the terms of its outstanding bonds, which also restrict the Company's incurrence of debt and liens. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Financing."

Our operations are subject to risks, some of which are not insurable.

        The business of mining, smelting and refining copper, zinc and other metals is subject to a number of risks and hazards, including industrial accidents, labor disputes, unusual or unexpected geological conditions, changes in the regulatory environment, environmental hazards and weather and other natural phenomena, such as earthquakes. Such occurrences could result in damage to, or destruction of, mining operations resulting in monetary losses and possible legal liability. In particular, surface and underground mining and related processing activities present inherent risks of injury to personnel and damage to equipment. We maintain insurance against many of these and other risks, which may not provide adequate coverage in certain circumstances. Insurance against certain risks, including certain liabilities for environmental pollution or hazards as a result of exploration and production, is not

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generally available to us or other companies within the mining industry. We do not have, and do not intend to obtain, political risk insurance. These or other uninsured events may adversely affect our financial condition and results of operations.

The loss of one of our large customers could have a negative impact on our results of operations.

        The loss of one or more of our significant customers could adversely affect our financial condition and results of operations. In 2002, 2003 and 2004, our largest customer accounted for approximately 6.9%, 7.4% and 10.7%, respectively, of our sales. Additionally, our five largest customers in each of 2002, 2003 and 2004 collectively accounted for approximately 25.8%, 29.9% and 33.7%, respectively, of our sales.

Our selected combined financial information for 2000 and 2001 has been derived from financial statements that are unaudited.

        This prospectus supplement includes Audited Combined Financial Statements as of December 31, 2004, and for each of the years in the three-year period ended December 31, 2004. This prospectus supplement also includes certain combined financial information as of and for the years ended December 31, 2000 and 2001. The 2000 and 2001 combined financial information is unaudited and has been derived from audited stand-alone financial statements of SPCC and Minera México; however, the combined financial information for 2000 and 2001 has been prepared by our management on a basis which we believe is consistent with the basis on which the Audited Combined Financial Statements have been prepared.

        Our selected historical financial information for 2000 and 2001, which is incorporated into the accompanying prospectus by reference to SPCC's annual report on Form 10-K for 2004, is derived from financial statements that were audited by Arthur Andersen LLP, independent certified public accountants. Subsequently, Arthur Andersen ceased to audit publicly-held companies.

Deliveries under our copper sales agreements can be suspended or cancelled by our customers in certain cases.

        Under each of our copper sales agreements, we or our customers may suspend or cancel delivery of copper during a period of force majeure. Events of force majeure under these agreements include acts of nature, labor strikes, fires, floods, wars, transportation delays, government actions or other events that are beyond the control of the parties. Any suspension or cancellation by our customers of deliveries under our copper or other sales contracts that are not replaced by deliveries under new contracts or sales on the spot market would reduce our cash flow and could adversely affect our financial condition and results of operations.

The copper mining industry is highly competitive.

        We face competition from other copper mining and producing companies around the world. Although we are currently among the lowest cost copper producers in our region, we cannot assure you that competition from lower cost producers will not adversely affect us in the future.

        In addition, mines have limited lives and, as a result, we must periodically seek to replace and expand our reserves by acquiring new properties. Significant competition exists to acquire properties producing or capable of producing copper and other metals.

        The mining industry has experienced significant consolidation in recent years, including consolidation among some of our main competitors, as a result of which an increased percentage of copper production is from companies that also produce other products and may, consequently, be more diversified than we are. We cannot assure you that the result of current or further consolidation in the industry will not adversely affect us.

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        Potential changes to international trade agreements, trade concessions or other political and economic arrangements may benefit copper producers operating in countries other than Peru and Mexico, where our mining operations are currently located. We cannot assure you that we will be able to compete on the basis of price or other factors with companies that in the future may benefit from favorable trading or other arrangements.

Increases in energy costs may adversely affect our results of operations.

        We require substantial amounts of fuel oil, electricity and other resources for our operations. Energy costs constitute approximately 22.8% of our cost of sales. We rely upon third parties for our supply of the energy resources consumed in our operations. The prices for and availability of energy resources may be subject to change or curtailment, respectively, due to, among other things, new laws or regulations, imposition of new taxes or tariffs, interruptions in production by suppliers, worldwide price levels and market conditions. For example, during the 1970s and 1980s, our ability to import fuel oil was restricted by Peruvian government policies that required us to purchase fuel oil domestically from a government-owned oil producer at prices substantially above those prevailing on the world market. In addition, in recent years the price of oil has risen dramatically due to a variety of factors. Disruptions in supply or increases in costs of energy resources could have a material adverse effect on our financial condition and results of operations.

We may be adversely affected by labor disputes.

        In the last several years we have experienced a number of strikes or other labor disruptions that have had an adverse impact on our operations and operating results. See "Business—Employees." For example, in Peru, on August 31, 2004, unionized workers at our mining units in Toquepala and Cuajone initiated work stoppages and sought additional wage increases based on high metals prices. The strike was resolved on September 13, 2004. In Mexico, on July 12, 2004, the workers of Mexicana de Cobre went on strike asking for the review of certain contractual clauses. Such a review was performed and the workers returned to work 18 days later. On October 15, 2004, the workers of Mexicana de Cananea went on strike, followed by the Mexicana de Cobre workers. The strike lasted for 6 days at Mexicana de Cobre and 9 days at Mexicana de Cananea. In each case, our operations at the particular mine ceased until the strike was resolved. We cannot assure you that we will not experience strikes or other labor-related work stoppages that could have a material adverse effect on our financial condition and results of operations.

Environmental, health and safety laws and other regulations may increase our costs of doing business, restrict our operations or result in operational delays.

        Our exploration, mining, milling, smelting and refining activities are subject to a number of Peruvian and Mexican laws and regulations, including environmental laws and regulations, as well as certain industry technical standards. Additional matters subject to regulation include, but are not limited to, concession fees, transportation, production, water use and discharge, power use and generation, use and storage of explosives, surface rights, housing and other facilities for workers, reclamation, taxation, labor standards, mine safety and occupational health.

        Environmental regulations in Peru and Mexico have become increasingly stringent over the last decade and we have been required to dedicate more time and money to compliance and remediation activities. We anticipate additional laws and regulations will be enacted over time with respect to environmental matters and such laws may be influenced by certain new Peruvian environmental laws imposing closure and remediation obligations on the mining industry. Our Mexican operations are also subject to the environmental agreement entered into by Mexico, the United States and Canada in connection with the North American Free Trade Agreement. The development of more stringent environmental protection programs in Peru and Mexico and in relevant trade agreements could impose constraints and additional costs on our operations and require us to make significant capital

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expenditures in the future. We cannot assure you that future legislative, regulatory or trade developments will not have an adverse effect on our business, properties, results of operations, financial condition or prospects.

Our metals exploration efforts are highly speculative in nature and may be unsuccessful.

        Metals exploration is highly speculative in nature, involves many risks and is frequently unsuccessful. Once mineralization is discovered, it may take a number of years from the initial phases of drilling before production is possible, during which time the economic feasibility of production may change. Substantial expenditures are required to establish proven and probable ore reserves through drilling, to determine metallurgical processes to extract the metals from the ore and, in the case of new properties, to construct mining and processing facilities. We cannot assure you that our exploration programs will result in the expansion or replacement of current production with new proven and probable ore reserves.

        Development projects have no operating history upon which to base estimates of proven and probable ore reserves and estimates of future cash operating costs. Estimates are, to a large extent, based upon the interpretation of geological data obtained from drill holes and other sampling techniques, and feasibility studies that derive estimates of cash operating costs based upon anticipated tonnage and grades of ore to be mined and processed, the configuration of the ore body, expected recovery rates of the mineral from the ore, comparable facility and equipment operating costs, anticipated climatic conditions and other factors. As a result, actual cash operating costs and economic returns based upon development of proven and probable ore reserves may differ significantly from those originally estimated. Moreover, significant decreases in actual or expected prices may mean reserves, once found, will be uneconomical to produce.

Our profits may be negatively affected by currency exchange rate fluctuations.

        Our assets, earnings and cash flows are influenced by various currencies due to the geographic diversity of our sales and the countries in which we operate. As some of our costs are incurred in currencies other than our functional currency, the U.S. dollar, fluctuations in currency exchange rates may have a significant impact on our financial results. These costs principally include electricity, labor, maintenance, operation contractors and fuel. For the year ended December 31, 2004, a substantial portion of our costs were denominated in a currency other than U.S. dollar. Operating costs are influenced by the currencies of the countries where our mines and processing plants are located and also by those currencies in which the costs of equipment and services are determined. The Peruvian nuevo sol, the Mexican peso and the U.S. dollar are the most important currencies influencing costs.

        The U.S. dollar is our functional currency and our revenues are primarily denominated in U.S. dollars. However, portions of our operating costs are denominated in Peruvian nuevos soles and Mexican pesos. Accordingly, when inflation in Peru or Mexico increases without a corresponding devaluation of the nuevo sol or peso, respectively, our financial position, results of operations and cash flows could be adversely affected. To manage the volatility related to the risk of currency rate fluctuations, we may enter into forward exchange contracts. We cannot assure you, however, that currency fluctuations will not have an impact on our financial condition and results of operations.

        Further, in the past there has been a strong correlation between copper prices and the exchange rate of the U.S. dollar. A strengthening of the U.S. dollar may therefore be accompanied by lower copper prices, which would negatively affect our financial condition and results of operations.

        We may be adversely affected by challenges relating to slope stability.

        Our open-pit mines get deeper as we mine them, presenting certain geotechnical challenges including the possibility of slope failure. If we are required to decrease pit slope angles or provide additional road access to prevent such a failure, our stated reserves could be negatively affected. Further, hydrological conditions relating to pit slopes, removal of material displaced by slope failures

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and increased stripping requirements could also negatively affect our stated reserves. We have taken actions in order to maintain slope stability, but we cannot assure you that we will not have to take additional action in the future or that our actions taken to date will be sufficient. Unexpected failure or additional requirements to prevent slope failure may negatively affect our results of operations and financial condition, as well as have the effect of diminishing our stated ore reserves.

We are controlled by Grupo México, which exercises significant influence over our affairs and policies and whose interests may be different from yours.

        Grupo México, S.A. de C.V. owns approximately 75.1% of our capital stock. In addition, certain of our officers and directors are also officers of Grupo México. We cannot assure you that the interests of Grupo México will not conflict with yours.

        Grupo México has the ability to determine the outcome of substantially all matters submitted for a vote to our stockholders and thus exercises control over our business policies and affairs, including the following:

•

the composition of our board of directors and, as a result, any determinations of our board with respect to our business direction and policy, including the appointment and removal of our officers;



•

determinations with respect to mergers and other business combinations, including those that may result in a change of control;



•

whether dividends are paid or other distributions are made and the amount of any dividends or other distributions;



•

sales and dispositions of our assets; and



•

the amount of debt financing that we incur.

        In addition, we have in the past engaged in, and expect to continue to engage in, transactions with Grupo México and its other affiliates that may present conflicts of interest. For additional information regarding the share ownership of, and our relationships with, Grupo México and its affiliates, see "Principal and Selling Stockholders" and "Related Party Transactions."

The price of our common stock may fluctuate significantly, which may result in losses for investors.

        The market price of our common stock has been and may continue to be volatile. For example, during the 52-week period ended December 31, 2004, the closing sales prices of our common stock as reported on the New York Stock Exchange ranged from a low of US$26.10 to a high of US$55.80. Our stock price can fluctuate as a result of a variety of factors beyond our control, including:

•

actual or anticipated fluctuations in copper or other metals prices;



•

actual or anticipated fluctuations in quarterly and annual results;



•

mergers and strategic alliances in the mining industry;



•

market conditions in the industry;



•

changes in government regulations;



•

fluctuations in our quarterly revenues and earnings and those of our publicly held competitors;



•

shortfalls in our operating results from levels forecast by securities analysts;



•

announcements concerning us or our competitors; and



•

the general state of the securities market.

        The market price of our stock may continue to fluctuate in response to these and other factors. We cannot assure you that the price of our common stock will not be volatile in the future or that our stockholders will not suffer losses.

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Future sales of common stock by some of our existing Peruvian institutional stockholders could cause our stock price to decline.

        Approximately 2% of our outstanding common stock is held by Peruvian pension funds. These pension funds are subject to regulation by the Superintendencia de Banca y Seguros (Banking and Insurance Commission, or SBS) in Peru and are limited as to the percentage of their investment portfolios that is classified as inversiones en el exterior (foreign investments), which are defined generally as investments in companies having more than 50% of their assets located outside of Peru. Prior to our acquisition of Minera México on April 1, 2005, substantially all of SPCC's assets were located in Peru. Thus, SPCC was treated as a domestic investment for purposes of these pension fund regulations. However, following the acquisition of Minera México, approximately 51% of our assets are located in Peru. The SBS has informed us that our status as a domestic investment will be reviewed by it on a quarterly basis and that, should the percentage of our consolidated assets located in Peru decrease to below 50%, we could be reclassified as a foreign investment. In the event of such reclassification, the Peruvian pension funds that currently own our common stock may have to sell all or a portion of these shares, which could cause the market price of our common stock to decline. The perception among investors that these sales may occur could produce the same effect.

We may be restricted from paying cash dividends on our common stock in the future.

        We have distributed a significant amount of our net income as dividends since 1996 and we anticipate paying significant amounts of dividends for the immediately foreseeable future, although we cannot assure you that this dividend practice will be maintained. Our dividend practice is subject to change at the discretion of our board of directors at any time. The determination of the amount of dividends to pay, if any, is subject to a number of factors, including our results of operations, financial condition, cash requirements, tax considerations, future prospects and other factors that our board of directors may deem relevant. Our ability to pay dividends is also subject to legal and contractual restrictions. In addition, we may become subject to limits on our ability to distribute dividends imposed by the governments of Peru, Mexico or other countries where we have significant operations. For example, from 1985 through 1990 we were subject to controls on repatriation of funds that limited the ability of our stockholders to receive dividends outside of Peru.

        In addition, we cannot assure you that the agreements governing our current and future indebtedness will permit us to pay dividends on our common stock. Further, a substantial amount of our revenue is attributable to our recently-acquired Minera México subsidiary that has its own contractual and other restrictions on the amount of dividends it can pay to us. We cannot assure you that the current or future dividend restrictions of Minera México or any of its subsidiaries will not limit out ability to pay dividends in the future.

Risks Associated with Doing Business in Peru and Mexico

        There is uncertainty as to the termination and renewal of our mining concessions.

        Under the laws of Peru and Mexico, mineral resources belong to the state and government concessions are required in both countries to explore for or exploit mineral reserves. In Peru, our mineral rights derive from concessions from the Peruvian Ministry of Energy and Mines for our exploration, exploitation, extraction and/or production operations. In June 2004, the Peruvian Congress enacted legislation imposing a royalty tax to be paid by mining companies in favor of the regional governments and communities where mining resources are located. Under the new law, we are subject to a 1% to 3% tax, based on sales, applicable to the value of the concentrates produced in our Toquepala and Cuajone mines. See "Business—Mining Rights and Concessions—Peru." In Mexico, our mineral rights derive from concessions granted, on a discretionary basis, by the Secretaría de Economía (Ministry of Economy), formerly known as Secretaría de Comercio y Fomento Industrial, pursuant to the Ley Minera (the Mining Law) and regulations thereunder.

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        Mining concessions in both Peru and Mexico may be terminated if the obligations of the concessionaire are not satisfied. In Peru, we are obligated to pay certain fees for our mining concession. In Mexico, we are obligated, among other things, to explore or exploit the relevant concession, to pay any relevant fees, to comply with all environmental and safety standards, to provide information to the Ministry of Economy and to allow inspections by the Ministry of Economy. Any termination or unfavorable modification of the terms of one or more of our concessions, or failure to obtain renewals of such concessions subject to renewal or extensions, could have a material adverse effect on our financial condition and prospects.

Peruvian economic and political conditions may have an adverse impact on our business.

        A significant part of our operations are conducted in Peru. Accordingly, our business, financial condition or results of operations could be affected by changes in economic or other policies of the Peruvian government or other political, regulatory or economic developments in Peru. During the past several decades, Peru has had a history of political instability that has included military coups and a succession of regimes with differing policies and programs. Past governments have frequently intervened in the nation's economy and social structure. Among other actions, past governments have imposed controls on prices, exchange rates and local and foreign investment as well as limitations on imports, have restricted the ability of companies to dismiss employees, have expropriated private sector assets (including mining companies) and have prohibited the remittance of profits to foreign investors.

        From 1985 through 1990, during the Alan García administration, government policies restricted our ability, among other things, to repatriate funds and import products from abroad. In addition, currency exchange rates were strictly controlled and all exports sales were required to be deposited in Peru's Banco Central de Reserva, where they were exchanged from U.S. dollars to the Peruvian currency at less-than-favorable rates of exchange. These policies generally had an adverse effect on our results of operations. Controls on repatriation of funds limited the ability of our stockholders to receive dividends outside of Peru but did not limit the ability of our stockholders to receive distributions of earnings in Peru.

        In July 1990, Alberto Fujimori was elected president, and his administration implemented a broad-based reform of Peru's political system, economy and social conditions aimed at stabilizing the economy, restructuring the national government by reducing bureaucracy, privatizing state-owned companies, promoting private investment, developing and strengthening free markets and enacting programs for the strengthening of basic services related to education, health, housing and infrastructure. After taking office for his third term in July 2000 under extreme protest, President Fujimori was forced to call for general elections due to the outbreak of corruption scandals, and later resigned in favor of a transitory government headed by the president of Congress, Valentín Paniagua.

        Mr. Paniagua took office in November 2000 and in July 2001 handed over the presidency to Alejandro Toledo, the winner of the elections decided in the second round held on June 3, 2001, ending two years of political turmoil. Since his election, President Toledo has retained, for the most part, the economic policies of the previous government, focusing on promoting private investment, eliminating tax exemptions, reducing underemployment and unemployment and privatizing state-owned companies in various sectors including energy, mining and public services. President Toledo also implemented fiscal austerity programs, among other proposals, in order to stimulate the economy. Despite Peru's moderate economic growth, the Toledo administration has at times faced public unrest spurred by the high rates of unemployment, underemployment and poverty. President Toledo has been forced to restructure his cabinet on several occasions to quell public unrest and to maintain his political alliances.

        Given that the Toledo administration continues to face a fragmented Congress and continuing public unrest, we cannot assure you that the government will continue its current economic policies or

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that Peru's recent economic growth will be sustained. In addition, presidential elections are expected to be held in Peru in the second quarter of 2006, which may mean a change in Peru's economic policies. Because we have significant operations in Peru, future Peruvian governmental actions could have an adverse effect on market conditions, prices and returns on our securities, and on our business, results of operations, financial condition, ability to obtain financing and prospects.

        There is a risk of terrorism in Peru relating to Sendero Luminoso and the Movimiento Revolucionario Tupac Amaru, which were particularly active in the 1980s and early 1990s. We cannot guarantee that acts by these or other terrorist organizations will not adversely affect our operations in the future.

Mexican economic and political conditions may have an adverse impact on our business.

        A significant part of our operations are based in Mexico. In the past, Mexico has experienced both prolonged periods of weak economic conditions and dramatic deterioration in economic conditions, characterized by exchange rate instability and significant devaluation of the peso, increased inflation, high domestic interest rates, a substantial outflow of capital, negative economic growth, reduced consumer purchasing power and high unemployment. An economic crisis occurred in 1995 in the context of a series of internal disruptions and political events including a large current account deficit, civil unrest in the southern state of Chiapas, the assassination of two prominent political figures, a substantial outflow of capital and a significant devaluation of the peso. We cannot assure you that such conditions will not recur, that other unforeseen negative political or social conditions will not arise or that such conditions will not have a material adverse effect on our financial condition and results of operations.

        On July 2, 2000, Vicente Fox of the Partido Acción Nacional (the National Action Party), or PAN, was elected president. Although his election ended more than 70 years of presidential rule by the Partido Revolucionario Institucional (the Institutional Revolutionary Party), or PRI, neither the PAN nor the PRI succeeded in securing a majority in the Mexican congress. In elections in 2003 and 2004, the PAN lost additional seats in the Mexican congress and state governorships. The lack of a majority party in the legislature and the lack of alignment between the legislature and the executive branch have resulted in legislative gridlock, which is expected to continue at least until the Mexican presidential elections in 2006. Such legislative gridlock has impeded the progress of structural reforms in Mexico, which may have a material adverse effect on the Mexican economy and cause disruptions to our operations. Furthermore, economic plans of the Mexican government in the past have not, in certain respects, fully achieved their objectives, and we cannot assure you that any reforms that are undertaken will achieve their stated goals. Because we have significant operations in Mexico, we cannot provide any assurance that current legislative gridlock and/or future political developments in Mexico, including the 2006 presidential and congressional elections, will not have a material adverse effect on market conditions, prices and returns on our securities, our ability to obtain financing, and our results of operations and financial condition.

Peruvian inflation, reduced economic growth and fluctuations in the nuevo sol exchange rate may adversely affect our financial condition and results of operations.

        Over the past several decades, Peru has experienced periods of high inflation, slow or negative economic growth and substantial currency devaluation. The inflation rate in Peru, as measured by the Indice de Precios al Consumidor and published by the Instituto Nacional de Estadística e Informática, the National Institute of Statistics, has fallen from a high of 7,649.7% in 1990 to 3.5% in 2004. The Peruvian currency has been devalued numerous times during the last 20 years. The devaluation rate has decreased from a high of 4,019.3% in 1990 to a negative of 5.2% in 2004. Our revenues are primarily denominated in U.S. dollars and our operating expenses are partly denominated in U.S. dollars. If inflation in Peru were to increase without a corresponding devaluation of the nuevo sol relative to the

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U.S. dollar, our financial position and results of operations, and the market price of our common stock, could be affected. Although the Peruvian government's stabilization plan has significantly reduced inflation and the Peruvian economy has experienced moderate growth in recent years, we cannot assure you that inflation will not increase from its current level or that such growth will continue in the future at similar rates or at all.

        Among the economic circumstances that could lead to a devaluation of the nuevo sol is the decline of Peruvian foreign reserves to inadequate levels. Peru's foreign reserves at March 31, 2005 were US$13.4 billion as compared to US$10.2 billion at December 31, 2003. We cannot assure you that Peru will be able to maintain adequate foreign reserves to meet its foreign currency denominated obligations or that Peru will not devalue its currency should its foreign reserves decline.

Mexican inflation, restrictive exchange control policies and fluctuations in the peso exchange rate may adversely affect our financial condition and results of operations.

        Although all of our Mexican operations' sales of metals are priced and invoiced in U.S. dollars, a substantial portion of our Mexican operations' cost of sales are denominated in pesos. Accordingly, when inflation in Mexico increases without a corresponding devaluation of the peso, as it did in 2000, 2001 and 2002, the net income generated by our Mexican operations is adversely affected.

        The annual inflation rate in Mexico was 5.7% in 2002, 4.0% in 2003 and 5.2% in 2004. The Mexican government has publicly announced that it does not expect inflation to exceed 4.0% in 2005. At the same time, the peso has been subject in the past to significant devaluation, which may not have been proportionate to the inflation rate and may not be proportionate to the inflation rate in the future. The value of the peso declined by 12.5% in 2002, 8.4% in 2003 and 0.6% in 2004.

        While the Mexican government does not currently restrict the ability of Mexican companies or individuals to convert pesos into dollars or other currencies, in the future, the Mexican government could impose a restrictive exchange control policy, as it has done in the past. We cannot assure you that the Mexican government will maintain its current policies with regard to the peso or that the peso's value will not fluctuate significantly in the future. The imposition of such exchange control policies could impair Minera México's ability to obtain imported goods and to meet its U.S. dollar-denominated obligations and could have an adverse effect on our business and financial condition.

Developments in other emerging market countries and in the United States may adversely affect the market value of our company.

        The market value of securities of companies with significant operations in Peru and Mexico is, to varying degrees, affected by economic and market conditions in other emerging market countries. Although economic conditions in such countries may differ significantly from economic conditions in Peru or Mexico, as the case may be, investors' reactions to developments in any of these other countries may have an adverse effect on the market value of the securities of issuers that have significant operations in Peru or Mexico.

        In addition, in recent years economic conditions in Mexico have increasingly become correlated to U.S. economic conditions. Therefore, adverse economic conditions in the United States could have a significant adverse effect on Mexican economic conditions. We cannot assure you that our market value would not be adversely affected by events in the United States or elsewhere, especially in emerging market countries.

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EXCHANGE RATES

Exchange Rates in Peru

        Since March 1991, there have been no exchange controls in Peru and all foreign exchange transactions are based on free market exchange rates. During the previous two decades, however, the Peruvian currency had experienced a significant number of large devaluations. Therefore, Peru has adopted and operated under various exchange rate control practices and exchange rate determination policies. These policies have ranged from strict control over exchange rates to market-determination of rates. Investors are allowed to purchase foreign currency at free market exchange rates through any member of the Peruvian banking system.

        The following table shows, for the periods and dates indicated, the period-end, average, high and low exchange rates for U.S. dollars, as published by the Banco Central de Reserva del Peru (Central Reserve Bank of Peru, or BCRP). The Federal Reserve Bank of New York does not report a noon buying rate for nuevos soles. The information in this table reflects Peruvian nuevos soles at historical values rather than in constant Peruvian nuevos soles. The high and low exchange rates provided in the table are the highest and lowest of the twelve month-end exchange rates for each year based on the BCRP exchange rate. The average rate for the years 2000 through 2004 is in each case the average of month-end exchange rates during such year.

(1)

Source: Banco Central de Reserva del Peru

The exchange rate for U.S. dollars as of April 19, 2005 was 3.259 nominal nuevos soles per U.S. dollar.

Exchange Rates in Mexico

        On December 21, 1994, Banco de México implemented a floating foreign exchange rate regime under which the peso is allowed to float freely against the U.S. dollar and other foreign currencies. Banco de México has indicated it will intervene directly in the foreign exchange market only to reduce what it deems to be excessive short-term volatility. Since mid-2003, Banco de México has been conducting auctions of U.S. dollars in an attempt to reduce the levels of its foreign reserves. Banco de México conducts open market operations on a regular basis to determine the size of Mexico's monetary base. Changes in Mexico's monetary base have an impact on the exchange rate. Banco de México may increase or decrease the reserve of funds that financial institutions are required to maintain. If the reserve requirement is increased, financial institutions will be required to allocate more funds to their reserves, which will reduce the amount of funds available for operations. This causes the amount of available funds in the market to decrease and the cost, or interest rate, to obtain funds to increase. The opposite happens if reserve requirements are lowered. This mechanism, known as "corto" or "largo," as the case may be, or more formally "the daily settlement balance target," represents a device used by Banco de México to adjust the level of interest and foreign exchange rates.

        We cannot assure you, however, that Banco de México will maintain its current policies with respect to the peso or that the peso will not depreciate significantly in the future. Moreover, we cannot

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assure you that the Mexican government will not impose exchange controls or otherwise restrict foreign exchange, including the exchange of pesos into U.S. dollars, in the future.

        Banco de México has provided for risk management and hedging mechanisms against fluctuations in the peso to dollar exchange rate. Banco de México allows Mexican banks and brokerage houses to participate in futures markets for the peso. In April 1995, the Chicago Mercantile Exchange introduced peso futures contracts and options on peso futures contracts and started trading these options and futures. On December 18, 1998, trading started at the Mexican Derivatives Exchange, including peso futures contracts.

        In the event of shortages of foreign currency, we cannot assure you that foreign currency would continue to be available to private-sector companies or that foreign currency needed by us to service foreign currency obligations would continue to be available without substantial additional cost.

        The following table sets forth, for the periods indicated, the period-end, average, high and low noon buying rate in New York City for cable transfers in pesos published by the Federal Reserve Bank of New York, expressed in pesos per U.S. dollar. The rates have not been restated in constant currency units and therefore represent nominal historical figures.

Source: Federal Reserve Bank of New York

On April 22, 2005 the noon buying rate was 11.036 pesos per U.S. dollar.

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CAPITALIZATION

        The following table sets forth our combined capitalization as of December 31, 2004. This table should be read in conjunction with our Audited Combined Financial Statements and the notes thereto included elsewhere in this prospectus supplement and is qualified in its entirety by the information contained therein. Our Audited Combined Financial Statements and the financial information in the table below reflect our April 1, 2005 acquisition of Minera México as a combination of businesses under common control, on a historical basis in a manner similar to a pooling of interests, reflecting the financial condition and results of operations for SPCC and Minera México on a combined basis. See "Financial and Other Information—Financial Information."

        Our capitalization will not change as a result of the combined offering because we are not issuing or selling shares in the offering and we will not receive any proceeds from the sale of the shares by the selling stockholders.

(1)

Cash, cash equivalents and marketable securities is not part of the calculation of our total capitalization.

        The following is a summary of transactions affecting our capitalization during the period from December 31, 2004 through April 20, 2005:

        On January 31, 2005, we signed a new credit facility for US$200.0 million. We borrowed the full US$200 million available under that facility and paid all of the US$199 million outstanding under our Peruvian bond program. On March 30, 2005 we prepaid US$120.0 million of the amount outstanding under Minera México's US$600 million syndicated credit facility. On March 1, 2005, we paid a cash dividend in the amount of US$100 million. On April 12, 2005, we declared a dividend of US$2.37 per share, totaling US$350 million. The dividend is payable May 13, 2005 to our stockholders of record as of April 29, 2005.

        As a result of the above-mentioned events our total debt has decreased during the period from December 31, 2004 to March 31, 2005 by US$119.0 million and our retained earnings has been reduced during the same period by US$452.0 million (including a US$2.0 million debt prepayment penalty).

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PRICE RANGE OF COMMON STOCK AND DIVIDEND INFORMATION

        Our common stock is traded on the New York Stock Exchange and the Lima Stock Exchange under the symbol "PCU." The following table sets forth, for the periods shown, the high and low per share sales prices for our common stock as reported on the New York Stock Exchange and the per share dividends paid during those periods. Dividends paid prior to April 1, 2005 are in respect of earnings of SPCC prior to its acquisition of Minera México. Therefore, the amounts of dividends paid set forth below differ from the amounts of dividends reflected in our Audited Combined Financial Statements or in the combined summary or selected financial information included in this prospectus supplement.

        On April 26, 2005, the last reported sale price for our common stock on the New York Stock Exchange was US$58.60 per share. As of January 31, 2005, there were approximately 2,738 holders of record of our common stock.

        On January 31, 2005, a special dividend of US$1.25 per share, totaling US$100 million, was declared and was paid on March 1, 2005. On April 12, 2005, a dividend of US$2.37 per share, totaling US$350 million, was declared, payable May 13, 2005, to our stockholders of record as of April 29, 2005. Investors in this offering will not be entitled to receive these dividends because shares purchased in this offering will be transferred after the record dates for the dividends.

        Set forth below is a chart that shows the amounts of quarterly dividends paid by us since 1996. Dividends paid prior to April 1, 2005 are the actual amounts paid with respect to SPCC prior to its acquisition of Minera México. Therefore, the amounts of dividends paid set forth below differ from the amounts of dividends reflected in our Audited Combined Financial Statements or in the combined summary or selected financial information included in this prospectus supplement.

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        We have distributed a significant amount of our net income as dividends since 1996. We anticipate paying significant amounts of dividends for the immediately foreseeable future, although we cannot assure you that this will be the case. The payment of dividends is subject to change at the discretion of our board of directors at any time. The determination of the amount of dividends to pay, if any, is subject to a number of factors, including our results of operations, financial condition, cash requirements, capital investment projects, tax considerations, future prospects and other factors that our board of directors may deem relevant. Our ability to pay dividends is also subject to legal and contractual restrictions. See "Risk Factors—Risks Relating to Our Business Generally—We may be restricted from paying cash dividends on our common stock in the future."

S-24

SELECTED COMBINED FINANCIAL INFORMATION

        The following tables present our selected combined financial information and other data for the years indicated. These tables should be read in conjunction with the Audited Combined Financial Statements and the notes thereto included elsewhere in this prospectus supplement and are qualified in their entirety by the information contained therein. Our Audited Combined Financial Statements and the financial information in the tables below reflect our acquisition of Minera México, completed April 1, 2005, as a combination of businesses under common control, on a historical basis in a manner similar to a pooling of interests, reflecting the financial condition and results of operations for SPCC and Minera México on a combined basis. See "Financial and Other information—Financial Information."

(1)

Financial information as of and for the years ended December 31, 2000 and 2001 is unaudited.

(2)

For purposes of these combined financial statements, the issuance of 67,207,640 shares related to the acquisition of Minera México have been reflected as if they had been outstanding as of January 1, 2000.

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Combined Balance Sheet