By Leah Schnurr NEW YORK (Reuters) - U.S. stocks were lower on Monday as brokerage upgrades for Home Depot Inc and Amazon.com Inc were offset by persistent worries about euro zone sovereign debt problems that dented sentiment. Over the weekend, European finance ministers tried to assure their counterparts in the Group of Seven industrialized nations that the euro zone's debt crisis is under control. They said they would make sure that Greece sticks with its budget-cutting plans. Worries about Greece's financial problems and their potential to spread to other euro zone countries or beyond has taken the steam out of Wall Street's rally in recent weeks. "This Greece issue is creating some headaches," said Kurt Brunner, portfolio manager at Swarthmore Group in Philadelphia, Pennsylvania. "It shakes confidence and creates that nervousness for the financial sector." Financials led the way down, with JPMorgan Chase & Co down 1.7 percent at $37.65 and the S&P financial index off 0.7 percent. The Dow Jones industrial average slipped 30.00 points, or 0.30 percent, to 9,982.23. The Standard & Poor's 500 Index dipped 1.35 points, or 0.13 percent, to 1,064.84. The Nasdaq Composite Index was off 2.01 points, or 0.09 percent, to 2,139.11. Dow component Home Depot gained 2.7 percent to $28.74 after Morgan Stanley upgraded it to "overweight" from "equal-weight". Morgan Stanley said it was optimistic about the home improvement chain's prospects as the housing market begins to recover. Amazon.com helped the Nasdaq fare better than the other two indexes, gaining 1.4 percent to $118.91 after Collins Stewart upgraded the company to "buy", citing a recent decline in its share price.