U.S. stocks retreated, giving the Standard & Poor’s 500 Index its biggest decline since December, after a report showed that the European economy contracted and as concern grew about the success of a Greece swap deal.

Concern about a slowdown grew today as Europe’s economy contracted in the fourth quarter after investment, exports and consumer spending dropped. The private investors that so far declared their participation in Greece’s debt restructuring hold about 20 percent of the bonds involved in a swap required for an international bailout. The goal of the swap, which runs through March 8, is to reduce by 53.5 percent the total of privately held Greek debt, helping avert an uncontrolled default.

The European Central Bank’s balance sheet surged to a record 3.02 trillion euros ($3.96 trillion) last week, 31 percent bigger than the German economy. Lending to euro-area banks jumped 310.7 billion euros to 1.13 trillion euros in the week ended March 2, the Frankfurt-based ECB said in a statement.

Dow 12,760.81      -202.00 -1.56%, Nasdaq 2,908.22        -42.26   -1.43%, S&P 500       1,343.17        -21.16   -1.55%

All 10 groups in the S&P 500 declined as commodity, financial and industrial shares had the biggest losses, falling at least 1.9 percent.

Alcoa Inc. (AA), the largest U.S. aluminum producer, dropped 3.4 percent to $9.53. Caterpillar Inc. (CAT), the world’s biggest maker of construction and mining-equipment, lost 3.2 percent to $106.56. Bank of America Corp. (BAC) retreated 2.8 percent to $7.75.

Merck & Co. fell 1.5 percent to $37.89. The second-largest U.S. drugmaker forecast first-quarter profit that was less than analysts’ estimates because of an “unfavorable” currency effect. Earnings excluding one-time items will be 95 cents to 98 cents a share, Merck said in a statement. That was less than the $1.01 average of 17 analyst estimates compiled by Bloomberg.

Nutrisystem Inc. tumbled 10 percent to $10.65. The provider of prepared meals to help clients lose weight forecast annual earnings per share of no more than 55 cents, falling short of the average analyst projection of 92 cents a share, data compiled by Bloomberg show.

Monster Worldwide Inc. added 8.8 percent to $8.18. The online recruiting service hired Stone Key Partners LLC and Bank of America Corp.’s Merrill Lynch to help it review strategic alternatives.