In January 2021, Griffin attracted criticism for the role played by Citadel in the GameStop short squeeze. On January 25, it was announced that Griffin's Citadel would invest $2 billion into Melvin Capital, which had suffered losses of more than 30% on account of its short positions, particularly on GameStop. On January 28, the trading platform Robinhood, favored by many traders involved in buying GameStop stock and options, abruptly announced that it would halt all purchases of GameStop securities except to cover shorts and would only allow these securities to be sold if already held (but not sold short); the price of GME stock declined steeply shortly thereafter. Because Robinhood receives a substantial portion of its revenue through a payment for order flow relationship with Citadel Securities LLC, 85% of which is owned by Griffin, many commentators criticized the potential for a conflict of interest when the same entity both plays the role of market-maker and also participates in the market that it makes; Griffin personally has been at the center of much discussion on this controversy. On February, 2021, Griffin testified before the House Financial Services Committee to address his role in the GameStop controversy; Griffin has donated money directly to four congresspeople on the committee, including Republicans French Hill, Andy Barr, Ann Wagner, and Bill Huizenga.