Exhibit 99.1


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Rush Street Interactive Closes Business Combination with dMY Technology Group, Inc.

– Common Stock and Warrants to Change Tickers and Trade on the NYSE under the new Ticker Symbols “RSI” and “RSI
WS”, respectively, Commencing on Wednesday, December 30, 2020 –

Chicago, Illinois – December 29, 2020 – Rush
Street Interactive, LP (“RSI”), one of the fastest-growing online casino and sports betting gaming companies in the United States, today announced that it has completed its previously announced business combination (the “Business
Combination”) with dMY Technology Group, Inc. (“dMY”). The Business Combination was approved at a special meeting of dMY’s stockholders held today.

Upon completion of the Business Combination, the combined company was renamed Rush Street Interactive, Inc. (the “Combined Company”). Beginning on
Wednesday, December 30, 2020, the dMY tickers will change and the Class A common stock and warrants of the Combined Company will commence trading on the New York Stock Exchange (the “NYSE”) under the new ticker symbols
“RSI” and “RSI WS,” respectively.

The Business Combination creates a leading online gaming company with U.S. market share in online
casino that is currently among the highest in the industry and a top online sports betting offering. RSI provides customers an array of offerings, including real-money online casino wagering, online and retail sports wagering, and social gaming. RSI
currently operates in six states – New Jersey, Colorado, Pennsylvania, Indiana, Illinois, Iowa – as well as Colombia, and it has secured market access in three additional states, including New York, with plans to target other
jurisdictions. RSI is growing quickly and has experienced a revenue increase of nearly five times from the first nine months of 2019 to the first nine months of 2020.

“Today marks a momentous milestone for RSI as we enter the public markets with a tremendous opportunity ahead of us,” said Greg Carlin, Chief
Executive Officer of RSI. “With online casino and online sports betting still in the early stages in the United States, we believe there is significant growth potential for our business in both existing and new markets. Eilers &
Krejcik estimates the total U.S. online casino market to be approximately $20 billion at maturity, and projects $15 billion for online sports betting. Our steadfast focus on customer experience and broad demographic reach, combined with
our proprietary technology platform, provide us with what we believe are material advantages to further our leadership position as online gaming continues to mature.”

“In a finite competitive landscape with high barriers to entry and strong secular growth trends, we were impressed with what RSI has been building since
2012 and are excited to partner with Greg Carlin, Richard Schwartz and their talented team as they continue to expand their market-leading platform,” said Niccolo de Masi, Chief Executive Officer of dMY Technology Group. “Through
RSI’s differentiated offerings and loyal user base driven by strong player trust and engagement, we believe RSI is ideally positioned to capitalize on the rapid growth in online casino and online sports betting. RSI is firmly committed to
operational excellence, and we believe it has the best product, the best tech platform and the best customer service in the market.”

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