(Adds investor comment, new details on Bombardier, closing stock prices)
* TSX down 47.98 points, or 0.3 percent, to 15,728.32
* Half of the TSX's 10 main groups were down
TORONTO, Oct 6 (Reuters) - Canada's main stock index retreated on Friday after touching a seven-month high in the previous session, as energy stocks, hurt by 3 percent drop in oil prices, drove the weaker finish.
The Toronto Stock Exchange's S&P/TSX composite index fell 47.98 points, or 0.3 percent, to finish at 15,728.32. Half of the index's 10 key sectors ceded ground.
The TSX closed at 15,776.30 on Thursday, its highest finish since Feb. 23, and added about 0.6 percent on the week, extending a monthlong rally that has helped bring the index back into positive territory for the year.
"The first eight months were pretty disappointing for the Canadian market compared to the U.S. September's been very good, so it's starting to catch up here," said John Kinsey, portfolio manager at Caldwell Securities.
Suncor Energy and Canadian Natural Resources were the most influential decliners on the index. Suncor fell 1.2 percent to C$43.5, while Canadian Natural Resources declined 2.1 percent to C$41.12. Cenovus Energy dropped 3.1 percent to C$12.05.
Oil and gas companies slumped 1.9 percent on oil prices that fell on profit-taking as well as renewed jitters about excess supply. Crude prices snapped a multiweek bull run, with U.S. crude settling at $49.29 a barrel, down 2.95 percent.
The heavily weighted financial sector slipped 0.2 percent, while industrials fell 0.4 percent.
Bombardier Inc rose 0.9 percent to C$2.21 even as the U.S. Commerce Department notched up proposed trade duties on the Canadian plane maker's CSeries jets to nearly 300 percent, affirming Boeing Co's complaint that Bombardier received illegal subsidies and dumped the planes at "absurdly low" prices.
The materials group, home to mining and other resource companies, added 0.2 percent as gold miners rebounded. Kirkland Lake Gold rallied 5.7 percent to C$17.46.
Element Fleet Management was the most influential gainer on the positive side. The stock surged 10.4 percent to end at C$9.98 on market talk of activist investors agitating for change. A company representative could not be immediately reached for comment.
Declining issues outnumbered advancing ones on the TSX by 138 to 107, for a 1.29-to-1 ratio on the downside.
Nine issues on the index posted a new 52-week high, while two posted new 52-week lows. (Reporting by Solarina Ho; Editing by Jonathan Oatis)