Stocks closed higher for a fourth straight week. Indexes are at record levels after surging this year on optimism about the economy and record earnings. The market is also being supported by ongoing stimulus from the Fed, which is keeping long-term borrowing costs at historically low levels. The Dow is up 17.2 percent for the year; the S&P 500 has gained 16.8 percent this year. After some lackluster reports on the economy Thursday, including an increase in applications for jobless benefits, Friday’s reports were a tonic for investors. The Conference Board said its index of leading economic indicators rose 0.6 percent last month.