NEW YORK — A slew of U.S. companies announced big profits Thursday, but investors spooked about the economy sold stocks anyway.

Investors shifted between buying and selling early Thursday, then stuck with selling after deciding that strong earnings results weren’t enough to make up for weak reports on jobs, housing and manufacturing.

The Dow Jones industrial average fell 68.65 points, or 0.5 percent, to close at 12,964.10. The broader Standard & Poor’s 500 index dropped 8.22 points, or 0.6 percent, to 1,376.92.

The Nasdaq composite fell 23.89 points, or 0.8 percent, to 3,007.56. Tech stocks could be in for some gains today following a strong earnings report after the closing bell Thursday from Microsoft.

Stock indexes fell after two relatively weak economic reports. An index of regional manufacturing compiled by the Philadelphia branch of the Federal Reserve dropped sharply, and the National Association of Realtors said home sales fell last month.

WASHINGTON — Americans bought fewer previously owned homes in March, a reminder that the housing market remains weak.

The National Association of Realtors said Thursday that home sales fell 2.6 percent last month to a seasonally adjusted annual rate of 4.48 million. That followed a revised 4.6 million sold in February.

A mild winter may have encouraged more people to buy earlier, essentially stealing sales from March.

The first three months of 2012 made up the best winter for sales in five years. The increase offers some encouragement ahead of the spring buying season. Still, sales remain far below the 6 million per year that economists equate with healthy markets.

WASHINGTON — The average rate on the 30-year fixed mortgage stayed near its lowest level on record, keeping home-buying and refinancing affordable.

Mortgage buyer Freddie Mac said the rate on the 30-year loan rose to 3.90 percent from 3.88 percent. The rate touched 3.87 percent in February, which was the lowest since long-term mortgages began in the 1950s.

The 15-year mortgage, which is popular with those refinancing, rose to 3.13 percent from 3.11 percent, an all-time low.

DALLAS — Southwest Airlines earned $98 million in the first quarter, helped by deals designed to blunt the pain of higher jet-fuel prices.

Excluding the fuel-hedging gains, which are like insurance against spikes in fuel prices, Southwest said Thursday it would have lost $18 million, less than analysts had expected.

Quarterly revenue rose 29 percent to $3.99 billion, reflecting the company’s bigger size since it bought AirTran Airways last year. The average one-way fare on Southwest and AirTran rose 5 percent in a year.

Southwest began serving Charleston last year.

MYRTLE BEACH — Spirit Airlines is adding direct flights from Myrtle Beach to Washington, D.C., and more flights to New York and Florida. The Sun News of Myrtle Beach reported that Spirit is adding flights to Niagara Falls and Plattsburgh in upstate New York and to Fort Lauderdale beginning in June.

Staff and wire reports