* TSX falls 50.38 points, or 0.41 percent, to 12,180.21 * Canadian Natural Resources falls 3.45 percent * Nine out of 10 main subgroups decline By John Tilak TORONTO, Nov 8 (Reuters) - Canada's main stock index fell on Thursday, led lower by the energy sector, which was hurt by a drop in Canadian Natural Resources Ltd after it cut its output forecast. Toronto stocks had a bumpy morning, at one point trading stronger, with investors sifting through positive U.S. jobs data on a day when the European Central Bank left interest rates unchanged. "It's a mixed bag. It's a day when people are trying to figure out what's going to happen in the United States," said John Kinsey, a portfolio manager at Caldwell Securities Ltd. "Are we going to see more of the same? It's too early to tell. So it may be a nothing market while it awaits developments." The Toronto Stock Exchange's S&P/TSX composite index was down 50.38 points, or 0.41 percent, at 12,180.21. Nine out of the 10 major subgroups were trading lower. The energy and materials subgroups were the biggest decliners, falling 0.97 percent and 0.94 percent, respectively. Shares of Canadian Natural fell 3.45 percent to C$27.94 after the country's biggest independent oil and gas producer reported a 57 percent fall in quarterly profit and cut its full-year forecast for crude oil and natural gas liquids output. It played the biggest role of any single stock in leading the market lower. Many investors remain concerned about resolving the issue of the U.S. fiscal cliff - a mix of tax increases and spending cuts due to extract some $600 billion from the economy starting early in the new year barring a deal. Kinsey said the fiscal cliff was his biggest concern as an investor. "It's awful scary. It has to be dealt with, and dealt with in an efficient manner," he said. The Canadian market's losses were partially offset by gains in Kinross Gold Corp, up 4.5 percent at C$9.77, and Sun Life Financial, up 3.20 percent at C$25.15. Kinross on Wednesday posted a third-quarter profit that topped expectations and said it expects to meet the higher end of its production targets for the year. Sun Life, Canada's No. 3 life insurer, said after markets closed on Wednesday that it swung back to a third-quarter profit due to better results from investments.