Exhibit 10.1

AMENDMENT NO. 1

TO

THE DYNEGY INC. SEVERANCE PLAN

WHEREAS, Dynegy Inc. (the “Company”) maintains the Dynegy Inc. Severance Plan
(the “Plan”);

WHEREAS, Section 11.5(a) of the Plan provides that the Compensation Committee of
the Board of Directors of the Company may amend the Plan subject to certain
limitations not applicable here; and

WHEREAS, on October 29, 2017, the Company entered into an Agreement and Plan of
Merger (as it may be amended from time to time, the “Merger Agreement”) with
Vistra Energy Corp. (“Vistra”) whereby, upon the terms and subject to the
conditions set forth therein, Dynegy will merge with and into Vistra (the
“Merger”).

NOW, THEREFORE, BE IT RESOLVED, that the Plan is hereby amended as follows,
effective as of immediately before but subject to the consummation of the Merger
(this “Amendment”):

 

  1. Section 2.1 (“Definitions”) is amended to include a new Section 2(w)
immediately following Section 2(v) to read in its entirety as follows (and as
applicable each successive section of the Plan shall be renumbered and
cross-references in the Plan shall be redesignated accordingly):

(w)    “Merger” shall mean the transactions contemplated by the Agreement and
Plan of Merger, dated October 29, 2017 and as it may be amended from time to
time, by and between the Company and Vistra Energy Corp., a Delaware
corporation.

 

  2. Section 2.1(f) (“Change in Control”) is amended to add the following
sentence at the end thereof:

Notwithstanding anything in this Plan to the contrary, the consummation of the
Merger shall constitute a Change in Control.

 

  3. Section 2.1(ff) (“Pro-Rata Bonus Payment”) is amended to read in its
entirety as follows:

(ff)    “Pro-Rata Bonus Payment” shall mean the value of (i) the bonus payment
payable to a Participant under the Annual Bonus Plan for the fiscal year of the
Company during which his termination occurs, determined (x) in respect of the
fiscal year in which the consummation of the Merger occurs, based on the actual
level of achievement of the applicable performance criteria as of the date of
the consummation of the Merger, with such level determined by the Board of
Directors of the Company (or a committee thereof) not later than immediately
prior to the consummation of the Merger or (y) in respect of any other fiscal
year, based on the actual performance of the Company, in each case of (x) and
(y), without application of any modifiers for individual performance, multiplied
by (ii) a fraction, the numerator of which is the number of days during the
period beginning on the first day of such fiscal year and ending on the date of
such termination, and the denominator of which is three hundred sixty-five
(365).

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  4. Section 4.1(b)(2) (“Bonus Following Severance”) is revised to read in its
entirety as follows:

(2)    Bonus Following Severance. A Participant shall be eligible to receive a
Pro-Rata Bonus Payment, which shall be paid, (x) in respect of the fiscal year
in which the consummation of the Merger occurs, as soon as practicable and in
any event within fourteen (14) days following the date on which the Release
becomes irrevocable or (y) in respect of any other fiscal year, subject to
Section 5.2 below, at the same time as bonus payments are paid under the terms
of the Annual Bonus Plan. In addition, a Participant shall be eligible to
receive any bonus payment payable to the Participant under the Annual Bonus Plan
for the fiscal year of the Company immediately preceding the fiscal year in
which the Participant’s Termination Date occurs which has not been paid as of
the Participant’s Termination Date, determined (x) if such prior fiscal year is
the year in which the consummation of the Merger occurred, based on the actual
level of achievement of the applicable performance criteria as of the date of
the consummation of the Merger without application of any modifiers for
individual performance, with such level determined by the Board of Directors of
the Company (or a committee thereof) not later than immediately prior to the
consummation of the Merger, and (y) if such prior fiscal year is any other year,
based on the actual performance of the Company.

 

  5. The second sentence of Section 5.2 (“Time and Form of Payment”) is revised
to read in its entirety as follows:

The Pro-Rata Bonus Payment, if any, provided (x) pursuant to Section 4.1(a) will
be paid to the Participant in one lump sum during the calendar year immediately
following the calendar year in which the Participant’s Termination Date occurs,
provided such payment shall be made not later than the date the bonus is paid to
other participants in the Annual Bonus Plan or (y) pursuant to Section 4.1(b)
will be paid as provided in Section 4.1(b)(2), in each case, provided that the
Release has been properly executed and has become irrevocable as described in
the prior sentence.

FURTHER RESOLVED, that this Amendment shall be of no force or effect in the
event the Merger Agreement is terminated before consummation of the Merger, and
the Plan is otherwise ratified and confirmed in all respects.