U.S. markets headed lower Monday after Group of 20 finance leaders failed to agree on increasing international aid to Europe. The lack of support for Europe, which is struggling to contain debt in Greece, Italy, Spain and Portugal, took the legs out from under stocks, given recent assessments that said Europe would fall into a mild recession in 2012. Stocks fell despite encouraging data from the National Association of Realtors, which said pending home sales rose 2 percent in January, twice what economists had expected. In midmorning trading on Wall Street, the Dow Jones industrial average was down 23.88 points or 0.18 percent to 12,959.07. The Standard & Poor\'s 500 index lost 1.92 points or 0.14 percent to 1,363.82. The Nasdaq composite index dropped 4.41 points or 0.15 percent t 2,959.34. The benchmark 10-year treasury note rose 14/32 to yield 1.931 percent. The euro fell to $1.3411 from Friday\'s $1.3449. Against the yen, the dollar fell to 80.43 yen from 81.20 yen. In Tokyo, the Nikkei 225 index fell 0.14 percent, 13.45 points, to 9,633.93.