Shares of the Grapevine, Texas, videogame retailer at last check rose 12% to $39.93.
Citron Research said on Twitter that it expects GameStop to drop to $20 a share.
"Tomorrow am at 11:30 EST Citron will livestream the 5 reasons GameStop $GME buyers at these levels are the suckers at this poker game," Citron Research said in a tweet. "Stock back to $20 fast. We understand short interest better than you and will explain."
GameStop did not immediately respond a request for comment.
Earlier this month, GameStop named three new directors as part of its agreement with RC Ventures, the company's second-largest shareholder.
One of the directors is Ryan Cohen, manager of RC Ventures and co-founder of pet-supplies specialist Chewy.com, which PetSmart purchased in 2017 for $3.35 billion.
GameStop said the three executives have "deep expertise in e-commerce, online marketing, finance and strategic planning."
Adding them to the board "will help us accelerate our transformation plans and fully capture the significant growth opportunities ahead for GameStop," said GameStop Chairwoman Kathy Vrabeck.
The company recently reported that comparable-store sales increased 4.8% and e-commerce sales quadrupled during the holiday shopping season. Total sales declined 3.1%.
Citron said that "there is no business that is more commoditized and competitive than having food delivered from the restaurant to your home."
DoorDash shares were up 7.3% to $200.87 at last check.