Veteran investment banker Kenneth Moelis left UBS in March 2007, ending a stint as president of its global investment bank to go into business for himself. Never one to think small, he says he envisioned Moelis & Co. as a modern, global version of “one of those great firms” like Drexel Burnham Lambert and Donaldson, Lufkin & Jenrette, where he worked before joining UBS.

The upheaval in the financial markets has crushed rivals big and small. But Moelis, 50, continues to dream of creating a major new M&A advisory practice for the global market. Even as announced global M&A activity declined 20 percent, to $3.2 trillion, for the first ten months of 2008, according to research firm Dealogic, Moelis & Co. advised...