Morgan Stanley has acknowledged that the Securities and Exchange Commission has asked CEO John Mack to testify at a deposition about any possible role he may have had in insider trading activity involving hedge fund Pequot Capital Management. Mack briefly served as chairman of Pequot last year before his return to Morgan Stanley. “John immediately responded that he is happy to meet with the commission staff, and he welcomes the opportunity to put to rest any issues surrounding this matter,” the firm said in a statement. Last month, former SEC attorney Gary Aguirre sued the agency, claiming he was fired after he expressed a desire to question an influential Wall Street figure – later identified as Mack – in the Pequot investigation. Aguirre has since sued for access to SEC documents that he feels would support his claim.