* TSX ends down 145.42 points, or 1.2 pct, at 12,273.57 * All 10 sectors lower in broad decline By Claire Sibonney TORONTO, Oct 9 (Reuters) - Canada's main stock index marked its lowest close in almost two weeks on Tuesday, tracking a sell-off in world equity markets after the IMF said the global economic slowdown is worsening. All 10 of the index's sectors fell on a wave of negative signals, including the stark warning from the IMF as it cut its growth forecasts for the second time since April and warned U.S. and European policymakers that failure to fix their economic ills would prolong the slump. Commodity and financial shares were among the hardest hit. Barrick Gold sank 3.7 percent to C$39.60, Goldcorp Inc lost 3.9 percent to C$43.45 and Manulife Financial fell 3 percent to C$11.95. "I think the IMF (report) is what people are paying attention to. But it struck me as being a little bit late ... current economic news coming out of the U.S. has been a little bit better rather than worse," said Ian Nakamoto, director of research at MacDougall, MacDougall & MacTier. Other news from Europe also kept investors on edge as uncertainty about when Spain will apply for a bailout worried markets, as did concerns about Greece's debt load. The Toronto Stock Exchange's S&P/TSX composite index ended down 145.42 points, or 1.17 percent, at 12,273.57. It was the weakest closing level since Sept. 26. Looking ahead to Wednesday, investors are expected to take their cue from U.S. aluminum producer Alcoa Inc, which kicked off earnings season with a third-quarter loss after Tuesday's market close. Analysts forecast third-quarter earnings of S&P 500 companies will drop 2.3 percent from the year-ago quarter, according to Thomson Reuters data, which would be the first drop in U.S. quarterly earnings in three years.