EXHIBIT 4.1 COMMON STOCK COMMON STOCK NUMBER SHARES CT This certificate is transferable See Reverse For Certain Definitions either in Chicago, IL or New York, NY CUSIP 192388 10 6 COGEN TECHNOLOGIES, INC. Incorporated Under the Laws of the State of Delaware This Certifies that is the owner of FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK, PAR VALUE $0.01 PER SHARE, OF COGEN TECHNOLOGIES, INC. 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. [COGEN TECHNOLOGIES SEAL APPEARS HERE] Dated: /s/ R.A. LYDECKER /S/ ROBERT C. McNAIR Secretary Charman of the Board Cogen Technologies, Inc. The corporation will furnish without charge to each stockholder who so requests the powers, designations, preferences and relative, participating, optional or other special rights of each class of stock or series thereof and the qualifications, limitations or restrictions of such preferences and/or rights. This certificate also evidences and entitles the holder hereof to certain rights as set forth in a Rights Agreement (the "Rights Agreement"), between Cogen Technologies, Inc. and Harris Trust and Savings Bank, dated as of the Record Date (as defined in Rights Agreement), the terms of which are hereby incorporated herein by reference and a copy of which is on file at the principal executive offices of Cogen Technologies, Inc. Under certain circumstances, as set forth in the Rights Agreement, the Rights described therein will be evidenced by separate certificates and will no longer be evidenced by this certificate. Cogen Technologies, Inc. will mail to the holder of this certificate a copy of the Rights Agreement without charge after receipt of a written request therefor. As described in the Rights Agreement, Rights issued to any Person who becomes an Acquiring Person (as those terms are defined in the Rights Agreement) shall become null and void. - -------------------------------------------------------------------------------- The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as if they were written out in full according to applicable laws or regulations: TEN COM- as tenants in common UNIF GIFT MIN ACT-__________________________Custodian _____________________ TEN ENT- as tenants by the entireties (Cust) (Minor) JT TEN - as joint tenants with right under Uniform Gifts to Minors of survivorship and not as Act ____________________________________________ tenants in common (State) Additional abbreviations may also be used though not in the above list. 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 ZIP CODE, OR ASSIGNEE) ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ _______________________________________________________________________ Shares of 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(S) AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER. SIGNATURE GUARANTEED: ____________________________________________________ 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. KEEP THIS CERTIFICATE IN A SAFE PLACE, IF IT IS LOST, STOLEN, OR DESTROYED, THE CORPORATION MAY REQUIRE A BOND OF INDEMNITY AS A CONDITION TO THE ISSUANCE OF A REPLACEMENT CERTIFICATE.