Gregg Lemkau, co-head of investment banking for Goldman Sachs & Co.Christopher Goodney | Bloomberg | Getty ImagesGoldman Sachs is losing one of its top dealmakers.Gregg Lemkau, a nearly-three decade veteran of the bank and co-head of its powerhouse investment banking division, is leaving Goldman at the end of the year, according to an internal memo sent Monday from CEO David Solomon.Lemkau, known as one of the top mergers bankers on Wall Street, has advised on hundreds of transactions since joining the bank in 1992.”Please join me in thanking Gregg for his many contributions to the firm, our clients and our people, and in wishing him and his family the very best in the years ahead,” Solomon said in the memo.Here’s the full memo from Solomon:Gregg Lemkau to Retire From Goldman SachsGregg Lemkau, co-head of the Investment Banking Division (IBD) and a member of the Management Committee, will retire from the firm at the end of the year.As co-head of IBD, Gregg has helped lead our efforts to continue to solidify and grow our pre-eminent investment banking franchise around the world. During his more than 28-year tenure at the firm, he has advised on hundreds of transactions, and has spent significant time advising our clients across all sectors globally while working in our offices in the US and in Europe. The firm has benefitted greatly from Gregg’s deep and expansive understanding of industries and markets, as well as his distinctive client service mindset.Gregg has also been instrumental in supporting our commitment to driving sustainable inclusive economic growth, helping conceive of and implement our board diversity initiative. He has partnered closely with our clients to improve their diversity representation pre-IPO, and through this critical work has underscored our firm’s conviction in the importance of having diverse voices represented at the table, both in business and society more broadly.In addition, Gregg has been a steward of the firm’s culture of teamwork and excellence throughout his nearly three decades at Goldman Sachs, and has been a key developer of talent and a mentor to so many of our current and future leaders. He has also sponsored a number of important programs to support our people, such as events organized by the Goldman Sachs Veterans Network and our Veterans Integration Program.Gregg has served with excellence since he joined us as an analyst in 1992 in Mergers & Acquisitions. Prior to assuming his current role as co-head of IBD, Gregg was co-head of Global Mergers & Acquisitions. He has also served as global co-head of the Technology, Media and Telecom Group, global co-head of the Healthcare Group and chief operating officer for the Investment Banking Division. Gregg is a member of the IBD Executive Committee, and previously served as chairman of the Firmwide Commitments Committee from 2011 to 2015 and as a member of the Partnership Committee. He was named managing director in 2001 and partner in 2002.Please join me in thanking Gregg for his many contributions to the firm, our clients and our people, and in wishing him and his family the very best in the years ahead.David M. Solomon This story is developing. Please check back for updates.