NEW YORK (CNN/Money) - U.S. stock markets tumbled early Monday on intelligence reports that al Qaeda terrorists may be seeking to target financial institutions.

After 10 minutes of trading, the Dow Jones industrial average (up 10.47 to 10,139.71, Charts), the Standard & Poor's 500 (up 1.29 to 1,101.72, Charts) index and the Nasdaq composite (up 6.30 to 1,887.36, Charts) all declined, led by the Nasdaq.

Homeland Security Secretary Tom Ridge said Sunday that intelligence from multiple sources shows sites in New York, New Jersey and Washington, D.C. to be at risk, prompting a raising of the security alert in those areas. Among the potential targets cited: the Citigroup buildings and the New York Stock Exchange in downtown New York City.

Shares of Citigroup (C: unchanged at $44.09, Research, Estimates) declined in the early going.

The news sparked a fresh round of declines in a much beaten-down stock market that registered declines throughout July. Last week seemed to mark something of a recovery, with the major indexes managing to close higher on the week.

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But many of the same concerns that had hurt markets remained -- chief among them, the price of oil.

Oil prices gained anew in response to the security threat. Light crude oil futures briefly touched a new all-time high of $43.92 a barrel in electronic trading Monday morning, before retreating. Brent crude oil futures also gained, before turning lower, falling 28 cents to $39.75 a barrel in London.

Among other commodities markets, COMEX gold added 90 cents to $394.60 an ounce.

Treasury prices rose, pushing the 10-year note yield down to 4.43 percent from 4.47 percent late Friday. The dollar declined versus the yen and euro.

In global trade, Asian markets fell Monday, and European markets were mostly weaker at midday there.