It's a different Citadel, from here: https://www.theverge.com/22251427/reddit-gamestop-stock-shor...
At least one Wall Street firm has taken heavy losses — Melvin Capital Management, which was shorting GameStop, among other bets. It’s been bailed out by Citadel, which, confusingly, is not the same thing as Citadel Securities. (Citadel is a hedge fund, not a market maker.)