The Dow Jones industrial average fell 43 points, or 0.3, to 14,496 in the first hour and half of trading. The Standard & Poor's 500 index fell four points, or 0.3 percent, to 1,559. The Nasdaq composite index fell 10 points, or 0.3 percent, to 3,248.
The S&P 500 was six points below its all-time closing high of 1,565, reached in October 2007. On Thursday, the Dow closed out a 10-day winning streak, its longest since November 1996.
Trading was tentative because investors fear that rising inflation will cause the Federal Reserve to retreat from policies aimed at boosting markets. The government said that consumer prices increased in February at the fastest pace in more than three years.
The increase was driven by a spike in gas prices; the core index, which excludes the volatile energy and food categories, increased more modestly. But both figures rose 2 percent compared with a year earlier, enough to get investors' attention, said Peter Tchir, who runs the hedge fund TF Market Advisors.
"It's real and it's a drag, and I think people are growing concerned that it can get out of control quickly," Tchir said. He said signs of economic improvement and inflation "make them wonder if there will be continued market pressure on the Fed" to end its bond-buying programs.
The market's recent rally to multi-year highs was fueled in part by the Fed's efforts to keep interest rates low and encourage investment.
A separate government report showed that U.S. factory output rose strongly in February because of an increase in auto production. Manufacturing is helping to drive economic growth after lagging for much of 2012.
Traders are processing big banks' scores on "stress tests" administered by the Federal Reserve. The Fed said late Thursday that JPMorgan Chase and Goldman Sachs both need better plans to cope with a severe recession. It gave them until September to revise their plans.
Still, the Fed allowed both banks to increase their dividends and buy back their stock, signaling that regulators believe the banks are fundamentally sound.
The stock of JPMorgan fell $1.07, or 2 percent, to $49.93.
Goldman's stock rose 71 cents to $154.73.
The yield on the 10-year Treasury note fell to just below 2 percent from 2.06 percent early Thursday, as demand increased for ultra-safe investments.
Among the other companies making big moves:
— Cruise ship operator Carnival Corp. fell 57 cents, or 2 percent, to $35.16. The company said passengers have been booking vacations at a slower pace after a series of high-profile mishaps.
— Krispy Kreme Doughnuts Inc. plunged after saying its fiscal fourth-quarter net income dropped sharply and fell short of expectations. The stock fell $1.27, or 9 percent, to $13.68.
— Teen apparel chain Aeropostale Inc. fell 91 cents, or 7 percent, to $13.60, after posting a loss in its fiscal fourth quarter and saying it expects another one in the current quarter.