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TORONTO, Nov 15 (Reuters) - Canada's main stock index fell to a three-week low on Wednesday as energy stocks again led a broad retreat on the back of sliding oil prices, pushing the market to its sixth straight daily decline after hitting an all-time high.
* The Toronto Stock Exchange's S&P/TSX composite index closed down 34.65 points, or 0.22 percent, at 15,878.48, its lowest close since Oct. 25.
* The index has retreated 1.6 percent since posting a record high of 16,131.79 last week.
* The energy group fell 0.5 percent, with Cenovus Energy Inc down nearly 2 percent to C$12.99, as oil prices fell for a fourth session after the U.S. government reported an unexpected increase in crude and gasoline stockpiles.
* U.S. crude prices settled 0.7 percent lower at $55.33 a barrel.
* Industrials declined 0.7 percent as railroad stocks lost ground.
* Seven of the index's 10 main groups ended lower.
* The largest percentage gainer on the TSX was Martinrea Intl, which rose 11.1 percent, after the car parts maker posted third-quarter earnings that beat expectations.
* The largest decliner was Canopy Growth Co, down 7.5 percent.
* Teck Resources Ltd, which Reuters reported has held talks with Dominic Barton, the global managing partner of consulting firm McKinsey & Co, about becoming the Canadian miner's next chairman, rose 0.5 percent to C$27.10.
* The TSX posted six 52-week highs and nine new lows, while volume was 176.93 million shares.
* Canada's biggest securities regulator is seeking a suspension of trading in two alternative trading venues run by Omega Securities Inc for failure to comply with market regulations, it said in an order dated Monday and released late on Tuesday. (Reporting by Fergal Smith and Alastair Sharp; Editing by Peter Cooney)