Exhibit 24.0

POWER OF ATTORNEY

Each of the undersigned hereby constitutes and appoints each of Timothy J. Curt, Steven G. Glenn and Robert B. Knauss, acting individually or jointly, with full power of substitution and resubstitution, to have full power and authority to act in its or his name, place and stead and on the undersigned’s behalf as its or his true and lawful attorney-in-fact to:

(1)                                 execute and deliver for and on behalf of the undersigned filings, reports and schedules in accordance with Section 13 of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), and Forms 3, 4 and 5 in accordance with Section 16(a) of the Exchange Act (including in each case any amendments, corrections, supplements or other changes thereto), and the rules promulgated under the Exchange Act;

(2)                                 do and perform any and all acts for and on behalf of the undersigned that may be necessary or desirable to complete and execute any such filings, reports, schedules and forms (including any amendments, corrections, supplements or other changes thereto) and timely file such with the United States Securities and Exchange Commission and any stock exchange, self-regulatory association or any other authority or person as may be required by law; and

(3)                                 take any other action of any type whatsoever in connection with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required of, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve in his discretion.

The undersigned hereby grants to each attorney-in-fact full power and authority to do and perform all and every act and thing whatsoever requisite, necessary and proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as such attorney-in-fact might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or his substitute or substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted.  The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming (i) any of the undersigned’s responsibilities to comply with the requirements of the Exchange Act or any liability for the undersigned’s failure to comply with such requirements or (ii) any obligation or liability that the undersigned incurs for profit disgorgement under Section 16(b) of the Exchange Act.

This Power of Attorney shall continue in full force and effect until revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact or by such attorneys-in-fact in a signed writing delivered to the undersigned.  This Power of Attorney hereby revokes the Power of Attorney dated December 12, 2012, and including any previously granted Power of Attorney, under which Scott A. Arenare was appointed to act on behalf of the undersigned, provided, however, it does not revoke, any other power of attorney that the undersigned has previously granted.

IN WITNESS WHEREOF, the undersigned have executed this Power of Attorney this 15th day of November, 2013.

Exhibit 99.1

Designated Filer: Warburg Pincus Private Equity IX, L.P.

Issuer & Ticker Symbol: Laredo Petroleum Holdings, Inc. [LPI]

Date of Event Requiring Statement: November 25, 2013

Explanation of Responses:

(1)  This Form 4 is filed on behalf of Warburg Pincus Private Equity IX L.P., a Delaware limited partnership (“WP IX”).  Warburg Pincus IX LLC, a New York limited liability company (“WP IX GP”), is the general partner of WP IX. Warburg Pincus Partners LLC, a New York limited liability company (“WP Partners”), is the sole member of WP IX GP. Warburg Pincus & Co., a New York general partnership (“WP”), is the managing member of WP Partners. Warburg Pincus LLC, a New York limited liability company (“WP LLC”), manages WP IX. Charles R. Kaye and Joseph P. Landy are the Managing General Partners of WP and the Co-Chief Executive Officers and Managing Members of WP LLC and may be deemed to control WP IX, WP IX GP, WP Partners, WP and WP LLC (together with Messrs. Kaye and Landy, the “Warburg Pincus Reporting Persons”).

(2) On November 25, 2013, WP IX distributed, which distribution did not constitute a purchase or sale of securities, an aggregate of 4,799,982 shares of common stock of Laredo Petroleum Holdings, Inc.  (“Common Stock” and such entity, the “Company”) held by WP IX to its partners on a pro rata basis, for no consideration.

By reason of the provisions of Rule 16a-1 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), each of the Warburg Pincus Reporting Persons may be deemed to be beneficial owners of the 55,855,020 shares of Common Stock of the Company held by WP IX. Pursuant to Rule 16a-1(a)(4) of the Exchange Act, each of the Warburg Pincus Reporting Persons, other than WP IX, herein states that this Form 4 shall not be deemed an admission that it or he is the beneficial owner of any of the shares of Common Stock of the Company reported in this Form 4. Each of the Warburg Pincus Reporting Persons disclaims beneficial ownership of the Common Stock of the Company, except to the extent it or he has a pecuniary interest in such shares of Common Stock.

Solely for the purposes of Section 16 of the Exchange Act, each of WP IX, WP IX GP, WP Partners, and WP may be deemed a director-by-deputization by virtue of their contractual right to nominate a representative to serve on the board of directors of the Company.

Information with respect to each of the Warburg Pincus Reporting Persons is given solely by such Warburg Pincus Reporting Person, and no Warburg Pincus Reporting Person has responsibility for the accuracy or completeness of information supplied by another Warburg Pincus Reporting Person.

Exhibit 99.2

Designated Filer: Warburg Pincus Private Equity IX, L.P.

Issuer & Ticker Symbol: Laredo Petroleum Holdings, Inc. [LPI]

Date of Event Requiring Statement: November 25, 2013

JOINT FILERS’ NAMES AND ADDRESSES

Exhibit 99.3

Designated Filer: Warburg Pincus Private Equity IX, L.P.

Issuer & Ticker Symbol: Laredo Petroleum Holdings, Inc. [LPI]

Date of Event Requiring Statement: November 25, 2013

JOINT FILERS’ SIGNATURES

*The Power of Attorney given by each of Warburg Pincus & Co., Mr. Kaye and Mr. Landy is filed as Exhibit 24.0 hereto.