The deputy head of investment of Morgan Stanley has left the firm. The departure was reported in the Wall Street Journal citing anonymous sources within the company.

Ji-Yeun Lee was a key lieutenant for Paul Taubman, who co-headed the company's investment banking operations. Last year, Taubman stepped down after his rival Colm Kelleher took over the helm of the unit.

When sought for comment by the Wall Street Journal, Lee declined to make any comment on her future plans. She was part of the firm's management committee and played behind the scene roles in her years as a banking executive with the firm.

In a separate move, Morgan Stanley had re-hired John Collins from Moelis & Co to become the global operations officer for the investment banking business. This is a new role in the firm as Collins was former mergers and acquisitions banker for Morgan Stanley.

Reuters sought comments from Morgan Stanley but could not obtain any outside of US business hours.