By Anora Mahmudova, MarketWatch

NEW YORK (MarketWatch) -- The U.S. stock market opened lower on Thursday, with the S&P 500 index retreating from record levels reached during the previous session, as disappointing earnings from Best Buy Co. Inc. and Citigroup Inc. dented sentiment.

The S&P 500 (SPX) opened down 5 points, or 0.3% at 1,843.07, easing off its record closing level reached on Wednesday.

The Dow Jones Industrial Average(DJI) opened down 65 points, or 0.4%, at 16,417.49. The Nasdaq Composite(RIXF) dropped 7.9 point at the open at 4,207.29.

Investors digested disappointing results from electronics retailer Best Buy and Citigroup. Follow stock market live blog.

Best Buy (BBY) plunged 30% after the retailer reported unexpectedly disappointing holiday sales as revenues dropped in the fourth quarter.

Citigroup Inc. (C) shares were down 2.8% as the company's fourth-quarter earnings missed Wall Street estimates.

Goldman Sachs Group Inc. (GS) was down 0.6% after topping analyst forecasts. Nonetheless, profit was down 19% as trading revenue sank.

In economic news, the number of Americans who applied last week for unemployment benefits fell slightly and is now back to a level that prevailed shortly before the Thanksgiving holiday, broadly in line with economists' forecasts. Separately, U.S. consumer prices rose a seasonally adjusted 0.3% in December, led by higher energy and shelter costs, the Labor Department said. The overall and core inflation numbers were also in line with expectations.

In a paper delivered at a Brookings Institution seminar on U.S. monetary policy, San Francisco Fed president John Williams said, "There are nagging concerns that large-scale asset purchases carry with them particular risks to the economy or the health of the financial system that we still don't fully understand."

He also said that the central bank's new forward guidance tool seems "overly simplified and prone to misinterpretation."

Fed Chairman Ben Bernanke will sit down at 11 a.m. Eastern time to review his record with Pulitzer-Prize winning author Liaquat Ahamed. Bernanke won't be working off prepared remarks. Read Spotlight on the Economy: Bernanke unscripted

Asset manager BlackRock Inc. (BLK) shares rose 3.6% after the firm said profit jumped 22% in the fourth quarter, as the amount of money it manages climbed 14%. The firm also raised its quarterly cash dividend to $1.93 per share.

Yahoo Inc. (YHOO) said Wednesday that Chief Operating Officer Henrique de Castro is leaving the company, effective Thursday. Shares dropped 1.3%. Read commentary: Yahoo COO exit may be a bad sign for fourth quarter.

SolarCity Corp. (SCTY) climbed 6.4% after Deutsche Bank analysts initiated coverage of the solar company with a buy rating and a $90 price target, according to news reports. Fellow solar company First Solar Inc. (FSLR) gained 0.8%.

Zoom Technologies Inc. (ZOOMD) revved up 21% as the tiny Chinese mobile and telecommunications investor rubber-stamped a deal late Wednesday to buy an online business travel provider.

More must-read stories from MarketWatch:

Big investors are betting against Bill Gross

Gold to fall 14.5% this year, banks say

Nestor soars 1,900% on investor confusion

Subscribe to WSJ: http://online.wsj.com?mod=djnwires