(Reuters) - Gregg Lemkau, the co-head of investment banking at Goldman Sachs Group Inc GS.N, is set to retire and will be replaced by company veteran Jim Esposito, according to an internal memo sent on Monday that was seen by Reuters. Lemkau, who was widely seen as a potential CEO candidate at Goldman, will join MSD Partners as chief executive officer. MSD Partners is the investment firm started by Michael Dell. (prn.to/2IK4R8R) One of the most high-profile dealmakers on Wall Street, Lemkau had jointly led Goldman’s mergers and acquisition department for a number of years, before being tasked to serve as co-head of investment banking in 2017. Under Lemkau, the bank dominated mergers and acquisitions among the top 20 financial advisers for 2019, according to data and analytics company GlobalData. (bit.ly/3f8bAp8) Goldman’s investment banking division has benefited from a number of large mergers and several high-profile IPOs in the third quarter this year, as dealmaking roared back to life following a pandemic-induced slowdown earlier this year. Esposito, who currently serves as the co-head of the company’s global markets division, will take over Lemkau’s role from January. (This story corrects paragraph 2 to say MSD Partners is the investment firm started by Michael Dell, not his family office)