Exhibit 99.1

Vistra Reports First Quarter 2020 Results

Above Expectations and Reaffirms 2020 Guidance

IRVING, Texas — May 5, 2020 — Vistra (NYSE: VST):

Financial Highlights

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COVID-19 Response

Growth Highlights

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Summary of Financial Results for First Quarter Ended March 31, 2020

For the three months ended March 31, 2020, Vistra reported Net Income from Ongoing Operations¹ of $62 million and Ongoing Operations Adjusted EBITDA¹ of $850 million. Vistra’s first quarter Adjusted EBITDA was $26 million² higher than first quarter 2019 results, driven by the acquisitions of Ambit Energy and Crius Energy and partially offset by lower generation results driven principally by lower capacity payments in its NY/NE and MISO segments.

Vistra reported first quarter Adjusted EBITDA from the Retail segment of $311 million, $54 million higher than first quarter 2019 results, driven primarily by the additions of Ambit Energy and Crius Energy. First quarter Adjusted EBITDA from the generation segments totaled $539 million,³ $28 million² lower than first quarter 2019 results due to lower results in the NY/NE and MISO segments, primarily driven by lower capacity revenues.

“First and foremost, our hearts go out to those who have been adversely impacted by the COVID-19 virus. While uncertainty remains, we are confident the American compassion, courage, ingenuity, and resilience will win out,” said Curt Morgan, Vistra’s president and chief executive officer. “Vistra started the year executing and delivering strong financial results and we are on track to continue to do so, even in the face of headwinds from the COVID-19 pandemic. Our business model – one that prioritizes a strong balance sheet and low-cost, integrated operations – is proving to be more important than ever during this time of economic uncertainty and volatility. We took actions early in the year to prepare our operations for this environment, ensuring the health and safety of our employees while fulfilling our obligation to provide an essential service. Reliable power has perhaps never been more important than it is today, allowing people to shelter in place and providing the essential electricity to keep lifesaving medical equipment running. Vistra takes very seriously its obligation to keep our employees healthy and safe and to provide the American people with affordable and reliable power. I am extremely proud of our team’s commitment to execution during these trying times.”

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Guidance

Vistra is reaffirming its 2020 Ongoing Operations Adjusted EBITDA and Ongoing Operations Adjusted FCFbG guidance ranges of $3,285 to $3,585 million and $2,160 to $2,460 million, respectively.

Capital Allocation

Vistra took steps within the quarter to reduce its long-term debt obligations. In Jan. 2020, Vistra redeemed the remaining $81 million of 8.000% senior unsecured notes due 2025, and in March 2020, Vistra Operations repurchased $100 million principal amount of Term Loan B-3 under the credit facility. On May 1, 2020, Vistra notified the holders of its 5.875% senior unsecured notes due 2023 that it will redeem all $500 million aggregate principal amount of such notes on June 1, 2020. Vistra continues to prioritize debt reduction in 2020 and, as a result, has not repurchased additional shares under its authorized share repurchase program since Nov. 2019. Net shares outstanding are approximately 488.6 million as of April 30, 2020. Vistra is on track to communicate its long-term capital allocation plan in late September of this year.

Liquidity

Vistra believes it has sufficient liquidity to continue business operations during the COVID-19 pandemic. In addition, Vistra’s maturities of long-term debt are relatively modest until 2023. As of March 31, 2020, Vistra had total available liquidity of approximately $1,834 million, including cash and cash equivalents of $717 million and $1,117 million of availability under its revolving credit facility. The company had $1,415 million of letters of credit outstanding as of March 31, 2020. In April 2020, Vistra repaid $550 million aggregate principal amount of revolving credit loans outstanding utilizing cash on hand.

Earnings Webcast

Vistra will host a webcast today, May 5, 2020, beginning at 8 a.m. ET (7 a.m. CT) to discuss these results and related matters. The live, listen-only webcast and the accompanying slides that will be discussed on the call can be accessed via the investor relations section of Vistra’s website at www.vistraenergy.com. A replay of the webcast will be available on the Vistra website for one year following the live event.

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About Non-GAAP Financial Measures and Items Affecting Comparability

“Adjusted EBITDA” (EBITDA as adjusted for unrealized gains or losses from hedging activities, tax receivable agreement impacts, reorganization items, and certain other items described from time to time in Vistra’s earnings releases),“Adjusted Free Cash Flow before Growth” (or “Adjusted FCFbG”) (cash from operating activities excluding changes in margin deposits and working capital and adjusted for capital expenditures (including capital expenditures for growth investments), other net investment activities, preferred stock dividends, and other items described from time to time in Vistra’s earnings releases), “Ongoing Operations Adjusted EBITDA” (adjusted EBITDA less adjusted EBITDA from Asset Closure segment) and “Ongoing Operations Adjusted Free Cash Flow before Growth” or “Ongoing Operations Adjusted FCFbG” (adjusted free cash flow before growth less cash flow from operating activities from Asset Closure segment before growth), are “non-GAAP financial measures.” A non-GAAP financial measure is a numerical measure of financial performance that excludes or includes amounts so as to be different than the most directly comparable measure calculated and presented in accordance with GAAP in Vistra’s consolidated statements of operations, comprehensive income, changes in stockholders’ equity and cash flows. Non-GAAP financial measures should not be considered in isolation or as a substitute for the most directly comparable GAAP measures. Vistra’s non-GAAP financial measures may be different from non-GAAP financial measures used by other companies.

Vistra uses Adjusted EBITDA as a measure of performance and believes that analysis of its business by external users is enhanced by visibility to both net income prepared in accordance with GAAP and Adjusted EBITDA. Vistra uses Adjusted Free Cash Flow before Growth as a measure of liquidity and believes that analysis of its ability to service its cash obligations is supported by disclosure of both cash provided by (used in) operating activities prepared in accordance with GAAP as well as Adjusted Free Cash Flow before Growth. Vistra uses Ongoing Operations Adjusted EBITDA as a measure of performance and Ongoing Operations Adjusted Free Cash Flow before Growth as a measure of liquidity and Vistra’s management and board of directors have found it informative to view the Asset Closure segment as separate and distinct from Vistra’s ongoing operations. The schedules attached to this earnings release reconcile the non-GAAP financial measures to the most directly comparable financial measures calculated and presented in accordance with U.S. GAAP.

Media

Meranda Cohn

214-875-8004

Media.Relations@vistraenergy.com

Analysts

Molly Sorg

214-812-0046

Investor@vistraenergy.com

About Vistra

Vistra (NYSE: VST) is a premier, integrated, Fortune 350 energy company based in Irving, Texas, providing essential resources for customers, commerce, and communities. Vistra combines an innovative, customer-centric approach to retail with safe, reliable, diverse, and efficient power generation. The company brings its products and services to market in 20 states and the District of Columbia, including six of the seven competitive markets in

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the U.S. and markets in Canada and Japan, as well. Serving nearly 5 million residential, commercial, and industrial retail customers with electricity and natural gas, Vistra is the largest competitive residential electricity provider in the country and offers over 40 renewable energy plans. The company is also the largest competitive power generator in the U.S. with a capacity of approximately 39,000 megawatts powered by a diverse portfolio including natural gas, nuclear, solar, and battery energy storage facilities. In addition, the company is a large purchaser of wind power. The company is currently constructing a 300-MW/1,200-MWh battery energy storage system in Moss Landing, California, which will be the largest of its kind in the world when it comes online. Vistra is guided by four core principles: we do business the right way, we work as a team, we compete to win, and we care about our stakeholders including our customers, our communities where we work and live, our employees, and our investors. Learn more about our environmental, social, and governance efforts and read the company’s sustainability report at https://www.vistraenergy.com/sustainability/

Cautionary Note Regarding Forward-Looking Statements

The information presented herein includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements, which are based on current expectations, estimates and projections about the industry and markets in which Vistra Energy Corp. (“Vistra”) operates and beliefs of and assumptions made by Vistra’s management, involve risks and uncertainties, which are difficult to predict and are not guarantees of future performance, that could significantly affect the financial results of Vistra. All statements, other than statements of historical facts, that are presented herein, or in response to questions or otherwise, that address activities, events or developments that may occur in the future, including such matters as activities related to our financial or operational projections, the potential impacts of the COVID-19 pandemic on our results of operations, financial condition and cash flows, projected synergy, value lever and net debt targets, capital allocation, capital expenditures, liquidity, projected Adjusted EBITDA to free cash flow conversion rate, dividend policy, business strategy, competitive strengths, goals, future acquisitions or dispositions, development or operation of power generation assets, market and industry developments and the growth of our businesses and operations (often, but not always, through the use of words or phrases, or the negative variations of those words or other comparable words of a future or forward-looking nature, including, but not limited to: “intends,” “plans,” “will likely,” “unlikely,” “believe,” “confident”, “expect,” “seek,” “anticipate,” “estimate,” “continue,” “will,” “shall,” “should,” “could,” “may,” “might,” “predict,” “project,” “forecast,” “target,” “potential,” “goal,” “objective,” “guidance” and “outlook”), are forward-looking statements. Readers are cautioned not to place undue reliance on forward-looking statements. Although Vistra believes that in making any such forward-looking statement, Vistra’s expectations are based on reasonable assumptions, any such forward-looking statement involves uncertainties and risks that could cause results to differ materially from those projected in or implied by any such forward-looking statement, including, but not limited to: (i) adverse changes in general economic or market conditions (including changes in interest rates) or changes in political conditions or federal or state laws and regulations; (ii) the ability of Vistra to execute upon the contemplated strategic and performance initiatives and to successfully integrate acquired businesses; (iii) actions by credit ratings agencies; (iv) the severity, magnitude and duration of pandemics, including the COVID-19 pandemic, and the resulting effects on our results of operations, financial condition and cash flows; and (v) those additional risks and factors discussed in reports filed with the Securities and Exchange Commission by Vistra from time to time, including the uncertainties and risks discussed in the sections entitled “Risk Factors” and “Forward-Looking Statements” in Vistra’s annual report on Form 10-K for the year ended December 31, 2019 and any subsequently filed quarterly reports on Form 10-Q.

Any forward-looking statement speaks only at the date on which it is made, and except as may be required by law, Vistra will not undertake any obligation to update any forward-looking statement to reflect events or circumstances after the date on which it is made or to reflect the occurrence of unanticipated events. New factors emerge from time to time, and it is not possible to predict all of them; nor can Vistra assess the impact of each such factor or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement.

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VISTRA ENERGY CORP.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited) (Millions of Dollars, Except Per Share Amounts)

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VISTRA ENERGY CORP.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Unaudited) (Millions of Dollars)

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VISTRA ENERGY CORP.

NON-GAAP RECONCILIATIONS - ADJUSTED EBITDA

FOR THE THREE MONTHS ENDED MARCH 31, 2020

(Unaudited) (Millions of Dollars)

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VISTRA ENERGY CORP.

NON-GAAP RECONCILIATIONS - ADJUSTED EBITDA

FOR THE THREE MONTHS ENDED MARCH 31, 2019¹

(Unaudited) (Millions of Dollars)

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VISTRA ENERGY CORP.

NON-GAAP RECONCILIATIONS - 2020 GUIDANCE¹

(Unaudited) (Millions of Dollars)