Citadel, headquartered in Chicago, handles $10 billion of investor funds.
Much of the company's investment success depends on an intricate series of secret computer codes. Friday night, two men, both Citadel employees at the time, have been indicted by a federal grand jury.
They are charged with trying to steal those secret codes and then covering their tracks when they were caught.
With a command center in Chicago, Citadel is one of the world's largest hedge fund managers. Employees are entrusted with and expected to guard the firm's secret computer trading codes known as alphas.
Friday night, according to a newly filed 23-count federal indictment, a pair of Citadel technology employees tried to infiltrate the company's elaborate security net and steal the codes for a competitor.
Authorities say Yihao "Ben" Pu and Sahil "Sonny" Uppal plotted to "surreptitiously download and transmit Citadel's confidential business information" via email accounts, their own computers and external drives.
Pu was charged and arrested in the case a year and a half ago, but at that time he was accused alone.
Friday night, the superseding indictment charges the second Citadel employee Sonny Uppal.
When the scheme was first exposed, prosecutors now say both men dumped some of the computer equipment into a sanitary canal near Wilmette Harbor.
Authorities say divers discovered electronic evidence in the water that contained Citadel's alphas, considered the building blocks of the firm's success.
Pu has been free on bond but had to surrender his passport, denying him the opportunity to visit China. Photos of his past trips have been posted on his personal website.
That site is among many that Pu is under court order to avoid. Pu is a Cornell University graduate. Authorities say the scheme to steal Citadel's secret codes began just two months after he started working for the company.
He and the newly charged ex-employee, Sahil Uppal, worked for Citadel until summer of 2011.
Neither of them could be reached for comment Friday.