Stocks ended higher in volatile trading Thursday as investors weighed fears about mounting tension in Iran against a report that indicated better-than-expected U.S. economic growth.

The Dow rose 48.39, or 0.39 percent, to 12,348.75. The index climbed as high as 12,381.91 during the morning session.

Broader stock indicators also finished higher. The Standard & Poor's 500 index rose 5.30, or 0.37 percent, to 1,422.53, and the Nasdaq composite index edged up 0.78, or 0.03 percent, to 2,417.88.

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The major indexes bounced around, and spent most of the session looking for direction as crude prices surged to a six-month high. Investors remain nervous about the West's response to British sailors held captive in Iran, and oil prices crossed the $66 mark.

This offset the Commerce Department's final measure of fourth-quarter gross domestic product, which showed growth of 2.5 percent. That could help quell concerns the economy is slowing too quickly. At the same time, strong economic growth could make it harder for the inflation-wary Federal Reserve to cut short-term interest rates.

Investors also bought-and-sold stocks to window dress their portfolio ahead of Saturday's end of the first quarter. The modest advance snapped a three-day losing streak for the Dow Jones industrials.

"The market is at a pivotal point," said Scott Fullman, director of investment strategy for Israel A. Englander & Co. "The market has become more volatile, and more sensitive, to news items."

Bonds slipped, with the yield on the benchmark 10-year Treasury note rising to 4.64 percent from 4.62 percent late Wednesday. The dollar fell against other major currencies, while gold prices tumbled.

Oil prices extended their gains Thursday after settling at their highest level since mid-September on Wednesday amid political tensions in the Middle East. Declining U.S. supplies amid high demand also drove up prices. Light, sweet crude rose $1.95 to settle at $66.03 a barrel on the New York Mercantile Exchange, after rising as high as $66.50.

The recent rise in oil prices generally poses a concern as increased energy costs could curb consumer spending and add to inflationary pressures.

Wall Street got little feedback from policymakers after a number of Fed officials gave speeches. Federal Reserve Bank of Minneapolis President Gary Stern was upbeat about the U.S. economy, but refrained from connecting that outlook to the future path of monetary policy.

Richmond Fed President Jeffrey Lacker did not address the economy in his remarks to a community affairs research conference in Washington. He instead spoke about the recent rise in consumer credit defaults being caused by borrower's mistakes and problems with lender risk assessments.

Earlier in the session, the Labor Department released a report that showed the number of newly laid-off workers signing up for unemployment benefits last week declined. This suggests the job market is still in good shape even as the economy goes through a sluggish spell.

In corporate news, U.S. Steel Inc. announced it will acquire Lone Star Technologies Inc. (LSS) for $2.1 billion, which represents a 39 percent premium. U.S. Steel rose $3.61, or 3.7 percent, to $101.22, while Lone Star surged $17.66, or 36.5 percent, to $65.11.

RF Micro Devices Inc. (RFMD), which makes radio frequency components, warned that weaker demand from a major customer would hurt its first-quarter results. Shares fell 76 cents, or 10.8 percent, to $6.31.

Circuit board maker Multi-Fineline Electronix Inc. (MFLX) said its second-quarter sales and profit could decline from the first quarter. The stock fell $1.95, or 11.2 percent, to $15.55.

The Russell 2000 index of smaller companies rose 1.54, or 0.19 percent, at 798.94.

Advancing issues outnumbered decliners by about 2 to 1 on the New York Stock Exchange, where volume came to 2.81 billion shares, down from 2.88 billion on Wednesday.

Overseas, Japan's Nikkei stock average closed up 0.05 percent. Britain's FTSE 100 was up 0.91 percent, Germany's DAX index added 1.18 percent, and France's CAC-40 was rose 1.42 percent.

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