AlHijjah 08, 1436, September 22, 2015, SPA -- U.S. stocks closed mixed Monday as investors weighed a decline in biotechs and eyed comments from Federal Reserve (Fed) speakers. In U.S. economic news, August existing home sales fell more than expected to an annual rate of 5.31 million, a 4.8 percent drop. Atlanta Fed President Dennis Lockhart said that the central bank's decision to delay an interest rate increase last week was largely a "risk management" exercise to be sure recent market volatility would not become a drag on the U.S. economy. He said that he still expects the Fed to raise rates this year. In international economic news, Greece was also in focus following an election Sunday in which Alexis Tsipras' left-wing Syriza party returned to power with an unexpected election win, with a mandate to implement a rescue plan. The dollar traded one percent higher against major world currencies. Light sweet crude oil for October delivery gained $2.00 to $46.68 a barrel on the New York Mercantile Exchange. Gold futures lost $5.00 to $1,133.10 an ounce. The Dow Jones industrial average added 135, or 0.83 percent, to 16,519. The broader Standard & Poor's 500 index climbed 12, or 0.6 percent, to 1,969. The technology-heavy Nasdaq composite index rose 10, or 0.2 percent, to 4,837.