US economic growth slowed in the second quarter, underperforming economists' expectations and adding another wrinkle to the Federal Reserve's path forward, even as consumer spending remained strong. GDP rose at an annual rate of 1.5%, the Commerce Department said Thursday, below economists' estimates of 2% annual growth. The second quarter figures also showed a marked slowdown from the first quarter, when GDP grew 2.1% year over year. If prices keep inching up while growth slows, worries may spread about the potential for "stagflation," which is when growth stagnates but prices go up anyway. The Personal Consumption Expenditures index rose 3.7% year over year in June, in line with expectations, and up from a gain of 4.1% in May.