Megacap technology and growth stocks such as Apple Inc AAPL.O, off 1.37%, and Microsoft Corp MSFT.O, down 1.07% were among the biggest drags on the index as Treasury yields rose. By Chuck Mikolajczak NEW YORK, Aug 29 (Reuters) - U.S. stocks closed lower on Monday, adding to last week's sharp losses on nagging concerns about the Federal Reserve's determination to aggressively hike interest rates to fight inflation even as the economy slows. Despite the rebound, some investors remain worried as September approaches due to the historical weakness for stocks during the month and the anticipated hike from the Fed.