NEW YORK - Investors are fearing they may have bet too soon on an economic comeback.

Stocks ended mostly lower Monday as drops in prices for oil and other commodities spurred worries that demand for basic materials may remain slack. Indexes ended mixed but off of their lows for the day.

The drop in oil to a five-week low pushed energy and commodity stocks lower and sent investors into safe-haven parts of the market, like consumer goods producers. Occidental Petroleum slid 2.5 percent while Procter & Gamble, which makes Tide and Crest, rose 2 percent.

The back-and-forth trading Monday followed conflicting signs about the economy. Oil skidded on fears of weak demand, while a trade group's report found that activity in the services industry rose in June to its best level in nine months.

Investors have become more cautious in recent weeks following a strong rally that began in March. Some traders fear they might have been too optimistic about how soon the economy might recover from a recession that began in December 2007.

"The markets are becoming more realistic," said Subodh Kumar, global investment strategist at Subodh Kumar & Associates in Toronto. "We can't snap our fingers and have recovery."

According to preliminary calculations, the Dow Jones industrial average rose 44.13, or 0.5 percent, to 8,324.87, and the broader Standard & Poor's 500 index rose 2.30, or 0.3 percent, to 898.72. The technology-heavy Nasdaq composite index fell 9.12, or 0.5 percent, to 1,787.40.

Oil fell $2.68 to settle at $64.05 per barrel on the New York Mercantile Exchange. Last week, oil hit an eight-month high above $73.

In economic news, the Institute for Supply Management's services index rose to 47 in June from 44 in May, beating the expectation of 45.5 from economists polled by Thomson Reuters.

The relatively good showing, however, wasn't enough to assuage growing doubts about the economy that worsened last week on disappointing reports on consumer confidence and deep job cuts for June.

The stock market has relatively few guideposts to give it direction this week ahead of second-quarter earnings reports, which get under way on Wednesday with Dow component Alcoa Inc. but don't pick up speed until next week.

Sound results at a Treasury Department auction of $8 billion in 10-year Treasury Inflation-Protected Securities, or TIPS, helped reassure investors that the government will be able to finance its spending plans to help revive the economy.

An analyst upgraded his rating on American Express Co., saying that the credit card company would be among the least affected by regulatory changes and that worries about bad debt are easing.