Citadel has unwound more than 80% of the aggregate risk in the portfolio it acquired from Leopold Aschenbrenner's Situational Awareness hedge fund, Ken Griffin told clients in a Friday letter obtained by CNBC's Sara Eisen. The firm carried out more than 100 block trades with a combined market value of over $4 billion. Citadel began discussions to acquire some of the holdings on July 29, a day before CNBC's David Faber reported that Situational Awareness had been forced to sell all of its public stock positions after steep losses. Griffin also said Citadel's flagship multistrategy Wellington fund returned 5.94% in July, its strongest monthly performance since 2022, according to CNBC's earlier reporting.