Kelleher joined Morgan Stanley's fixed-income sales unit in 1989. Serving as the bank's CFO during the 2007-08 financial crisis, he strategically slashed Morgan Stanley's balance sheet, cutting back on fixed-income trading positions and helping the company's investment bank regain clients' confidence after hedge funds pulled their money. He also converted Morgan Stanley to a traditional bank holding company to take advantage of Federal Reserve funding and negotiated a $9 billion investment in Japan's Mitsubishi UFJ Financial Group.