UNITED STATES SECURITIES and EXCHANGE COMMISSION Washington, D.C

Use these links to rapidly review the document Table of contents Index to financial statements Table of Contents As filed with the Securities and Exchange Commission on October 7, 2011 Registration No. 333-176439 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 LAREDO PETROLEUM HOLDINGS, INC. (Exact name of registrant as specified in its charter) Delaware 1311 45-3007926 (State or other jurisdiction of (Primary Standard Industrial (IRS Employer incorporation or organization) Classification Code Identification No.) Number) 15 W. Sixth Street, Suite 1800 Tulsa, Oklahoma 74119 (918) 513-4570 (Address, including zip code, and telephone number, including area code, of registrant's principal executive offices) Kenneth E. Dornblaser Senior Vice President & General Counsel 15 W. Sixth Street, Suite 1800 Tulsa, Oklahoma 74119 (918) 513-4570 (Name, address, including zip code, and telephone number, including area code, of agent for service) Copies to: Christine B. LaFollette G. Michael O'Leary Akin Gump Strauss Hauer & Andrews Kurth LLP Feld LLP 600 Travis, Suite 4200 1111 Louisiana Street, 44th Floor Houston, Texas 77002 Houston, Texas 77002 (713) 220-4200 (713) 220-5800 Approximate date of commencement of proposed sale to the public: As soon as practicable after this registration statement becomes effective. 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, check the following box. o If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) 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 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 this Form is a post-effective amendment filed pursuant to Rule 462(d) 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 Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. (check one) Large accelerated filer o Accelerated filer o Non-accelerated filer Smaller reporting company o (Do not check if a smaller reporting company) 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, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine. Table of Contents Subject to completion, dated October 7, 2011 The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, and we are not soliciting an offer to buy these securities in any state where the offer or sale is not permitted. Prospectus shares Common stock This is the initial public offering of shares of common stock by Laredo Petroleum Holdings, Inc. Laredo is selling shares of common stock. The estimated initial public offering price is between $ and $ per share. We intend to apply to have our shares of common stock listed on the New York Stock Exchange under the symbol "LPI." Per share Total Initial public offering price $ $ Underwriting discounts and commissions $ $ Proceeds to Laredo, before expenses $ $ We have granted the underwriters an option for a period of 30 days from the date of this prospectus to purchase up to an additional shares of our common stock. Investing in our common stock involves a high degree of risk. Please read "Risk factors" beginning on page 14. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense. J.P. Morgan Goldman, Sachs & Co. BofA Merrill Lynch Wells Fargo Securities Tudor, Pickering, Holt & Co. SOCIETE GENERALE Mitsubishi UFJ Securities BMO Capital Markets BNP PARIBAS Scotia Capital Capital One Southcoast BOSC, Inc. BB&T Capital Markets Comerica Securities Howard Weil Incorporated , 2011 Table of Contents Table of contents Page Prospectus summary 1 Risk factors 14 Forward-looking statements 39 Use of proceeds 41 Dividend policy 41 Capitalization 42 Dilution 43 Selected historical combined financial data 44 Management's discussion and analysis of financial condition and results of operations 49 Business 83 Management 110 Executive compensation 119 Certain relationships and related party transactions 141 Corporate reorganization 144 Security ownership of certain beneficial owners and management 145 Description of capital stock 146 Shares eligible for future sale 151 Certain U.S. federal income tax considerations for non-U.S. holders of shares of our common stock 153 Certain ERISA considerations 158 Underwriting (conflicts of interest) 159 Legal matters 166 Experts 167 Where you can find more information 168 Index to financial statements F-1 Annex A: Glossary of oil and natural gas terms A-1 Annex B: Ryder Scott Company, L.P. summary of June 30, 2011 reserves B-1 You should rely only on the information contained in this prospectus or in any free writing prospectus we may authorize to be delivered to you. Neither we nor the underwriters have authorized anyone to provide you with additional or different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are offering to sell, and seeking offers to buy, our common stock only in jurisdictions where offers and sales are permitted. The information in this prospectus is accurate as of the date of this prospectus, regardless of the time of delivery of this prospectus or any sale of our common stock. Our business, financial condition, results of operation and prospects may have changed since that date. i Through and including , 2011 (25 days after the commencement of this offering), all dealers that effect transactions in our common stock, whether or not participating in this offering, may be required to deliver a prospectus. This delivery requirement is in addition to a dealer's obligation to deliver a prospectus when acting as an underwriter and with respect to their unsold allotments or subscriptions. This prospectus contains forward-looking statements that are subject to a number of risks and uncertainties, many of which are beyond our control. See "Risk factors" and "Forward-looking statements." Industry and market data This prospectus includes industry and market data that we obtained from independent industry publications, government publications or other published independent sources. These publications generally state that the information contained therein has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. While we believe that each of these publications is reliable, we have not independently verified any of the data from third-party sources nor have we ascertained the underlying economic or operational assumptions relied upon therein. ii Table of Contents Prospectus summary This summary highlights selected information contained elsewhere in this prospectus. You should read the entire prospectus, including the information presented under the headings "Risk factors," "Forward-looking statements" and "Management's discussion and analysis of financial condition and results of operations" and the pro forma condensed combined and historical combined financial statements and notes thereto included elsewhere in this prospectus before making an investment decision with respect to our common stock. Unless otherwise indicated, information presented in this prospectus assumes that the underwriters' option to purchase additional shares of common stock is not exercised. We have provided definitions for certain oil and natural gas terms used in this prospectus in the "Glossary of oil and natural gas terms" beginning on page A-1 of this prospectus. In this prospectus, the pro forma condensed combined and historical financial information, operational data and reserve information for Laredo and our recently acquired subsidiary Broad Oak Energy, Inc., a Delaware corporation ("Broad Oak" and subsequently renamed Laredo Petroleum—Dallas, Inc.), have been combined. Although the financial and other information is reported on a combined basis, such presentation is not necessarily indicative of the results that would have been obtained if Laredo had owned and operated Broad Oak from its inception. In addition, our estimated proved reserve information as of June 30, 2011 contained in this prospectus is based on a reserve report relating to our combined properties

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