* TSX closes down 14.90 points, or 0.12 percent, at 12,370.80 * Index weighed down by energy, materials sectors By Allison Martell TORONTO, Dec 24 (Reuters) - Canada's main stock index ended down after a quiet, shortened Christmas Eve trading session on Monday, as oil prices extended their retreat on worries about U.S. 'fiscal cliff' budget measures, pulling energy shares lower. With U.S. lawmakers suspending talks on the spending cuts and tax increases that could send the economy back into recession until after Christmas, the market was cautious. Rick Hutcheon, President and Chief Operating Officer at RKH Investments, said uncertainty around the U.S. fiscal cliff was weighing on the market. "We have to get past the fiscal cliff. That's obviously a negative," he said. World oil prices fell for a third straight session as the budget dispute threatened to hurt demand by the United States - the world's top oil consumer. Energy was the most influential negative sector, closing down 0.7 percent. There is no set date for budget talks to resume, and the two sides have only a few days between Christmas and Jan. 1, when $600 billion in spending cuts and tax increases start to take effect. But Hutcheon also cautioned that markets were quiet: "There is very little volume - you can't read too much into the transactions that are occurring today." "It's extremely quiet," said John Kinsey, Portfolio Manager at Caldwell Securities. "There's just nobody around." Kinsey, like most political experts and economists, expects a U.S. budget deal of some sort will come after Christmas. "They have been through this before and they usually just kick the can down the road," he added. "Something's going to get down, not probably what I would like to see, but something is always done." The Toronto Stock Exchange's S&P/TSX composite index closed down 0.12 percent, or 14.90 points, at 12,370.80. Canadian and U.S. equity markets closed early, shutting at 1 p.m. EST (1800 GMT) ahead of Tuesday's Christmas holiday. Canadian markets will remain closed through Wednesday's Boxing Day holiday. Financial stocks closed little changed, up 0.03 percent. The materials sector edged down 0.13 percent as copper slipped. The Thomson Reuters-Jefferies CRB Index, which tracks commodity prices, was down 0.35 percent. Canada Life, a unit of insurer Great-West Lifeco Inc , is close to a deal for state-rescued insurer Irish Life, a source familiar with the talks said on Sunday. On Monday, Great-West rose 0.5 percent to C$24.30. Chevron Corp's Canadian unit said it would buy a 50 percent stake in the Kitimat liquefied natural gas project and the proposed Pacific Trail Pipeline from EOG Resources Inc and Encana Corp. Encana fell 2.3 percent to C$19.66. After Friday's close, SNC-Lavalin Group Inc said a client had given notice that it would terminate an engineering, procurement and construction contract. But SNC said it did not anticipate a material impact on fourth-quarter earnings. Its shares closed up 0.8 percent at C$40.21. Outside the index, Sears Canada Inc rose 1.6 percent to C$10.83 after it said its chief financial officer would resign effective Jan. 4. The company, majority-owned by Sears Holdings Corp is pushing for a turnaround after several quarters of precipitous declines in same-store sales.