July 28 (Reuters) - Investment manager T. Rowe Price Group TROW.O on Friday reported a better-than-expected second-quarter profit, as a rebound in markets helped boost assets under management at the firm. The S&P 500 .SPX gained 15.9% in the first six months of the year, bolstered by expectations the U.S. Federal Reserve could get inflation under control without pushing the economy into a deep recession. "Stronger equity markets helped lift revenue from first-quarter levels," T. Rowe CEO Rob Sharps said.