Stocks were little changed on Monday after gyrating between negative and positive territory in the first half hour as worsening sentiment about the global credit environment countered optimism about economic growth.

Tightening lending standards threaten to slow or halt the heavy pace of corporate buy-outs that have fueled a rally in equities.

In the latest sign of problems in the home lending market, American Home Mortgage Investment Corp. said its banks were demanding that it put up more cash after the mortgage lender was forced to write down the value of its mortgage and security portfolios.

We have certainly disturbed investor psychology with talk of problems in the subprime market and the inability to finance takeovers, said Al Kugel, chief investment strategist at Atlantic Trust in Chicago. I don't think it will affect the general economy, but it's giving people pause when it comes to buying stocks.

The Dow Jones industrial average was down 13.65 points, or 0.10 percent, at 13,251.82. The Standard & Poor's 500 Index was down 1.14 points, or 0.08 percent, at 1,457.81. The Nasdaq Composite Index was up 0.03 points at 2,562.27.

U.S. equities suffered their worst week in nearly five years last week.

American Home Mortgage shares were halted on the NYSE but had plunged 39 percent in trading before the opening bell, falling to $6.39 from Friday's close at $10.47.

Monday's headlines lacked the typical flurry of takeover and buyout announcements seen on many past Mondays this year.

In one deal that did emerge industrial conglomerate Ingersoll-Rand Co. Ltd. planned to sell its Bobcat machinery business and two other units to South Korea's Doosan Infracore.

Ingersoll-Rand shares rose 4.3 percent to $50.30 on the NYSE.

Among the companies reporting quarterly earnings on Monday was Dow component Verizon Communications Inc., which reported higher earnings that met Wall Street estimates.

Verizon shares were down 2.4 percent to $40.99 on the NYSE.

On Friday the Dow Jones industrial average was down 208.10 points, or 1.54 percent, at 13,265.47. The Standard & Poor's 500 Index was down 23.71 points, or 1.60 percent, at 1,458.95. The Nasdaq Composite Index was down 37.10 points, or 1.43 percent, at 2,562.24.

U.S.