U.S. stocks fell, sending the Dow Jones Industrial Average toward the lowest level on a closing basis this year, amid concern Greece may leave the euro and as Dell Inc. tumbled on a disappointing revenue forecast.

Stocks fell even after a report showed that demand for new U.S. homes increased more than forecast in April as low prices and mortgage interest rates drew buyers.

All 10 groups in the S&P 500 retreated today as commodity, technology and financial shares had the biggest losses. Citigroup fell 2.4 percent to $26.27. Bank of America (ВАС) slid 1.3 percent to $6.89.

Technology shares, which comprise 20 percent of the S&P 500, retreated 1.6 percent as 66 of its 71 stocks retreated.

Dell tumbled 18 percent, the biggest decline in the S&P 500, to $12.42. The forecast, paired with a first-quarter sales and earnings miss, pointed to problems endemic to Dell, Steve Felice, Dell’s president, said in a conference call. The sales team focused on individual products instead of packages of hardware and software, he said.

Some of the largest technology companies retreated. Hewlett-Packard Co. (HPQ), which reports quarterly results after the market close, slumped 4.5 percent to $20.80. Intel Corp. (INTC), the world’s biggest chipmaker, declined 3.7 percent to $25.06.

Facebook added 3.6 percent to $32.11. The shares fell below its $38 IPO price on May 21. The offering valued Facebook at 107 times trailing 12-month earnings, more than every S&P 500 member except Amazon.com Inc. and Equity Residential. The slump reinforced concern that the IPO was priced too high.

Ford Motor Co. jumped 1.4 percent to $10.33. The automaker was raised to investment grade by Moody’s Investors Service yesterday, enabling Executive Chairman Bill Ford, great-grandson of the founder, to reclaim the blue oval logo he put up as collateral for a loan.