(Bloomberg) -- Morgan Stanley tapped Arnaud Blanchard to replace Pawan Passi, the executive put on leave amid a sweeping U.S. probe into how Wall Street handles big stock trades.

Blanchard, who joined the firm in 2004, was named head of Americas equity syndicate, according to an internal memo seen by Bloomberg News. In appointing Blanchard, who has been chief operating officer of the firm’s global capital markets business since 2018, Morgan Stanley is filling the role with an executive who was charged with running the day-to-day operational functions and executing business strategy for the unit.

A representative for Morgan Stanley didn’t immediately comment. 

Passi was placed on leave in November as U.S. authorities examined his involvement in block trades as part of an investigation into whether banks improperly alerted certain clients to market-moving transactions, Bloomberg News reported. 

Morgan Stanley disclosed last month that regulators and prosecutors are investigating various aspects of its block-trading business, acknowledging the firm itself is under scrutiny. Passi, who led the firm’s communications with investors for equity transactions, is among a number of individuals whose activities are under review. 

U.S. authorities haven’t accused Passi of any wrongdoing. 

(Updates with background from second paragraph.)

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