* TSX closes down 52.61 points, or 0.42 percent, at 12,446.86 * Rona falls 11.6 pct as Lowe's walks away from bid * Declines across sectors as Fed euphoria fades By Alastair Sharp TORONTO, Sept 17 (Reuters) - Canada's main stock index fell on Monday, hurt by a drop in shares of retailer Rona Inc after a takeover proposal fell through and by fading euphoria over last week's aggressive move by the U.S. Federal Reserve to spur growth. Shares of home-improvement chain Rona fell 11.6 percent to C$11.29 after Lowe's Cos Inc withdrew its C$1.8 billion ($1.86 billion) proposal to bid for the Quebec-based company. The sharp sell-off made Rona one of the single biggest decliners on the Toronto Stock Exchange's S&P/TSX composite index. The index ended the day down 52.61 points, or 0.42 percent, at 12,446.86. Nine of its 10 main sectors fell with the heaviest drops in its financial, mining, and oil and gas sectors. The fall followed several strong sessions of gains late last week on the back of a new round of stimulus measures by the U.S. Federal Reserve. On Friday, the index hit a five-month high. "We're taking a breather here, Thursday and Friday were very good days. Nothing goes straight up or straight down," said John Kinsey, portfolio manager at Caldwell Securities. Some energy stocks were sideswiped by a sharp selloff in the price of crude, which eliminated nearly six days of gains. Major producer Suncor Energy Inc was down 0.9 percent at C$34.02 - Others bucked the trend, including smaller Crescent Point Energy Corp, which rose 3.9 percent to C$43.74 in a move that Kinsey ascribed to analyst upgrades. Pipeline company Enbridge Inc added 1 percent to C$38.81. Gold miners featured on the list of gainers as bullion slipped much less drastically than oil. After starting the day stronger, the country's biggest banks and insurers turned negative. Manulife Financial Corp was the single biggest weight on the index, down 1.3 percent at C$12.46. Diversified miner Teck Resources Ltd also weighed, down 3.8 percent at C$31.78, after moving up strongly last week. "It's just some sober reassessment of last week's events, no more, no less," said John Ing, president of Maison Placements Canada.