For the second time in as many weeks, a former executive of collapsed futures broker Refco has pleaded guilty to fraud.

Robert Trosten, who served as CFO until 2004, a year before the firm collapsed, admitted he helped hide hundreds of millions in losses from banks, auditors and investors. One of the latter, Boston private equity giant Thomas H. Lee Partners, paid $507 million for a 57% stake in Refco, which also provided clearing and prime brokerage services, in 2004.

Refco hid the losses in a company controlled by former CEO Phillip Bennett, who is facing life in prison after pleading guilty on Friday. Santo Maggio, who headed the firm’s offshore unit, pleaded guilty in December. Refco’s former president, Tone Grant, and a former outside lawyer to the futures broker, Joseph Collins, still face trial.