Exhibit 4.1

Exhibit 4.1

INCORPORATED UNDER THE LAWS OF THE STATE OF TEXAS

PREFERRED STOCK

PC

ATP OIL & GAS CORPORATION

PREFERRED STOCK

CUSIP 00208J 70 2

SEE REVERSE FOR CERTAIN DEFINITIONS

THIS CERTIFIES THAT

IS THE OWNER OF

FULLY PAID AND NON-ASSESSABLE SHARES OF 8% CONVERTIBLE PERPETUAL PREFERRED STOCK, PAR VALUE $.001 PER SHARE, OF

ATP OIL & GAS CORPORATION transferable on the books of the Corporation by the holder hereof in person or by duly authorized attorney upon surrender of this certificate properly endorsed. This certificate is not valid until countersigned by the Transfer Agent and registered by the Registrar.

Witness the facsimile seal of the Corporation and the facsimile signatures of its duly authorized officers.

Dated:

CHAIRMAN OF THE BOARD

SECRETARY

COUNTERSIGNED AND REGISTERED:

AMERICAN STOCK TRANSFER & TRUST COMPANY, LLC

(NEW YORK, NY) TRANSFER AGENT AND REGISTRAR

BY

AUTHORIZED SIGNATURE

ABnote North America

711 ARMSTRONG LANE

COLUMBIA, TENNESSEE 38401

(931) 388-3003

SALES: HOLLY GRONER 931-490-7660

PROOF OF: SEPTEMBER 28, 2009

ATP OIL & GAS CORPORATION

TSB 00336

OPERATOR: AP

NEW

PLEASE INITIAL THE APPROPRIATE SELECTION FOR THIS PROOF: OK AS IS OK WITH CHANGES MAKE CHANGES AND SEND ANOTHER PROOF Colors Selected for Printing: Intaglio prints in SC-20 DARK BROWN.

COLOR: This proof was printed from a digital file or artwork on a graphics quality, color laser printer. It is a good representation of the color as it will appear on the final product. However, it is not an exact color rendition, and the final printed product may appear slightly different from the proof due to the difference between the dyes and printing ink.

A full statement of the designations, preferences, limitations and relative rights of the shares of each class of stock of the Corporation authorized to be issued is set forth in the Restated Articles of Incorporation of the Corporation, as amended, on file in the Office of the Secretary of State of the State of Texas. The Restated Articles of Incorporation of the Corporation, as amended, on file in the Office of the Secretary of State of the State of Texas, deny the preemptive right of shareholders to acquire unissued or treasury shares of the Corporation. The Corporation shall furnish a copy of its Restated Articles of Incorporation, as amended, to the record holder of this Certificate without charge upon written request to the Secretary of the Corporation at its principal place of business in Houston, Texas.

THIS SECURITY (OR ITS PREDECESSOR) WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND THIS SECURITY AND ANY COMMON STOCK ISSUABLE UPON CONVERSION THEREOF MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF THIS SECURITY IS HEREBY NOTIFIED THAT THE SELLER OF THIS SECURITY MAY BE RELYING ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY RULE 144A THEREUNDER.

THE HOLDER OF THIS SECURITY AGREES FOR THE BENEFIT OF THE CORPORATION THAT (A) THIS SECURITY AND THE COMMON STOCK ISSUABLE UPON CONVERSION HEREOF MAY BE OFFERED, RESOLD, PLEDGED OR OTHERWISE TRANSFERRED, ONLY (I) IN THE UNITED STATES TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT) IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (II) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF AVAILABLE) OR (III) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH OF CASES (I) THROUGH (III) IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES, AND (B) THE HOLDER WILL, AND EACH SUBSEQUENT HOLDER IS REQUIRED TO, NOTIFY ANY PURCHASER OF THIS SECURITY OR ANY COMMON STOCK ISSUABLE UPON CONVERSION THEREOF FROM IT OF THE RESALE RESTRICTIONS REFERRED TO IN (A) ABOVE. IN ANY CASE, THE HOLDER HEREOF WILL NOT, DIRECTLY OR INDIRECTLY, ENGAGE IN ANY HEDGING TRANSACTIONS WITH REGARD TO THIS SECURITY EXCEPT AS PERMITTED UNDER THE SECURITIES ACT.

THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE PROVISIONS OF A STATEMENT OF RESOLUTIONS ESTABLISHING AND DESIGNATING THE CONVERTIBLE PREFERRED STOCK OF THE CORPORATION. THESE SECURITIES MAY NOT BE TRANSFERRED EXCEPT IN ACCORDANCE WITH SUCH STATEMENT OF RESOLUTIONS.

THIS CERTIFICATE IS IN GLOBAL FORM AND IS REGISTERED IN THE NAME OF THE DEPOSITORY TRUST COMPANY (“DTC”) OR A NOMINEE THEREOF. THIS CERTIFICATE MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY DTC TO A NOMINEE OF DTC OR BY A NOMINEE OF DTC TO DTC OR ANOTHER NOMINEE OF DTC OR BY ANY SUCH NOMINEE TO A SUCCESSOR OF DTC OR A NOMINEE OF SUCH SUCCESSOR DEPOSITORY.

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF DTC TO THE CORPORATION OR THE TRANSFER AGENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM – as tenants in common

TEN ENT – as tenants by the entireties

JT TEN – as joint tenants with right of survivorship and not as tenants in common

UNIF GIFT MIN ACT– Custodian

(Cust) (Minor)

Under Uniform Gifts to Minors

Act (State)

Additional abbreviations may also be used though not in the above list.

ASSIGNMENT

For Value Received, hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE

PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE, OF ASSIGNEE

Shares of the Common Stock represented by the within Certificate, and do hereby irrevocably constitute and appoint

Attorney to transfer the said shares on the books of the within-named Corporation, with full power of substitution in the premises.

Dated

X

X

NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER.

Signature(s) Guaranteed

By

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM), PURSUANT TO S.E.C. RULE 17Ad-15.

ABnote North America

711 ARMSTRONG LANE

COLUMBIA, TENNESSEE 38401

(931) 388-3003

SALES: HOLLY GRONER 931-490-7660

PROOF OF: SEPTEMBER 28, 2009

ATP OIL & GAS CORPORATION

TSB 00336

OPERATOR: AP

NEW

PLEASE INITIAL THE APPROPRIATE SELECTION FOR THIS PROOF: OK AS IS OK WITH CHANGES MAKE CHANGES AND SEND ANOTHER PROOF