Sec Form 4 Filing - ECP ControlCo, LLC @ DYNEGY INC. - 2018-01-09

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ECP ControlCo, LLC 2. Issuer Name and Ticker or Trading Symbol DYNEGY INC. [ DYN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 51 JOHN F. KENNEDY PARKWAY, SUITE 200 3. Date of Earliest Transaction (MM/DD/YY) 01/09/2018 (Street) SHORT HILLS, NJ07078 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 01/09/2018 S 5,250,000 D $ 11.79 14,291,152 I See footnotes ( 1 ) ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ECP ControlCo, LLC 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X ENERGY CAPITAL PARTNERS III, LLC 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X Energy Capital Partners GP III, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X ENERGY CAPITAL PARTNERS III, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X ENERGY CAPITAL PARTNERS III-A, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X Energy Capital Partners III-B (Terawatt IP), LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X ENERGY CAPITAL PARTNERS III-C, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X Terawatt Holdings GP, LLC 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X Terawatt Holdings, LP 51 JOHN F. KENNEDY PARKWAY SUITE 200 SHORT HILLS, NJ07078 X Signatures ECP ControlCo, LLC By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners III, LLC By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners GP III, LP By: Energy Capital Partners III, LLC, its general partner By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners III, LP By: Energy Capital Partners GP III, LP, its general partner By: Energy Capital Partners III, LLC, its general partner By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners III-A, LP By: Energy Capital Partners GP III, LP, its general partner By: Energy Capital Partners III, LLC, its general partner By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners III-B (Terawatt IP), LP By: Energy Capital Partners GP III, LP, its general partner By: Energy Capital Partners III, LLC, its general partner By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Energy Capital Partners III-C, LP By: Energy Capital Partners GP III, LP, its general partner By: Energy Capital Partners III, LLC, its general partner By: ECP ControlCo, LLC, its managing member By: /s/ Andrew D. Singer, Manging Member 01/11/2018 Signature of Reporting Person Date Terawatt Holdings GP, LLC By: /s/ Andrew D. Singer, Secretary and General Counsel 01/11/2018 Signature of Reporting Person Date Terawatt Holdings, LP By: Terawatt Holdings GP, LLC, its general partner By: /s/ Andrew D. Singer, Secretary and General Counsel 01/11/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Terawatt Holdings, LP is the record holder of the securities reported herein. ECP Control Co, LLC ("ECP Control Co") is the managing member of Energy Capital Partners III, LLC ("ECP GP"), which is the general partner of Energy Capital Partners GP III, LP ("ECP Fund GP"), which is the general partner of each of Energy Capital Partners III, LP, Energy Capital Partners III-A, Energy Capital Partners III-B (Terawatt IP), LP and Energy Capital Partners III-C, LP (collectively, the "ECP Funds"), which are the sole members of Terawatt Holdings GP, LLC ("Terawatt GP"), which is the general partner of Terawatt Holdings, LP. ( 2 )Douglas Kimmelman, Thomas Lane, Andrew Singer, Peter Labbat, Tyler Reeder and Rahman D'Argenio are the managing members of ECP ControlCo and share the power to vote and dispose of the securities beneficially owned by ECP ControlCo. As such, each of Terawatt GP, the ECP Funds, ECP Fund GP, ECP GP, ECP ControlCo and Messrs. Kimmelman, Lane, Singer, Labbat, Reeder and D'Argenio may be deemed to have or share beneficial ownership of the Common Stock held directly by Terawatt Holdings. Each such entity or individual disclaims any such beneficial ownership except to the extent of their pecuniary interest therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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