(Adds portfolio manager quotes, details on oil, background; updates prices)
* TSX down 193.34 points, or 1.50 percent, at 12,726.80
* Eight of the TSX's 10 main groups move lower
By Fergal Smith
TORONTO, Jan 6 (Reuters) - Canada's benchmark stock index fell for a sixth straight session on Wednesday as energy shares tracked crude oil prices lower, while heavyweight banks and railways declined on rising geopolitical tensions and growth worries.
The index was within reach of the Dec. 14 trough of 12,617.66, the lowest since August 2013. It follows an 11 percent loss in 2015, its worst year since the global financial crisis of 2008.
"From a trading perspective, there's just no bids anywhere," said Diana Avigdor, vice president, portfolio manager and head of trading at Barometer Capital Management.
The most influential movers included Suncor Energy Inc , the country's largest oil and gas company, which declined 3.7 percent to C$34.10 and pipeline company Enbridge Inc, which fell 3.1 percent to C$44.58.
The energy group overall dropped 3.7 percent, with crude oil prices plunging after data showing a shockingly large build-up of U.S. gasoline supplies fed fears that a global surplus was still growing.
U.S. crude prices settled at $33.97 a barrel, down 5.56 percent, while Brent crude lost 6.1 percent to $34.21.
The index's financials group retreated 1.8 percent, with Royal Bank of Canada off 1.7 percent to C$71.57.
The Toronto Stock Exchange's S&P/TSX composite index closed down 193.34 points, or 1.50 percent, at 12,726.80. Eight of the index's 10 main groups were in negative territory.
North Korea's reported successful nuclear test and disappointing Chinese data weighed on sentiment.
Canadian Pacific Railway Ltd fell 6.5 percent to C$164.93, while Magna International Inc was 3.7 percent lower at C$52.34.
"Canada is closer to the eye of the storm than say, U.S. is," Avigdor said, adding that the TSX's sensitivity to the commodity complex is a reason for investors to remain cautious.
Foreign investors have even more reason to stay sidelined, Avigdor said, citing concern that the Canadian dollar's correlation with oil will trigger currency losses as well as losses on stocks.
On the positive side, Valeant Pharmaceuticals International Inc rose 2.1 percent to C$144.10 after naming an interim CEO, while Loblaw Companies Ltd was up 2.7 percent at C$65.72.
Gold miners also rose, including Goldcorp Inc, which advanced 2.6 percent to C$16.62 and Barrick Gold Corp, which jumped 4.6 percent to C$11.19.
Gold futures rose 1.3 percent to $1,093 an ounce as investors sought a safe haven. (Additional reporting by Alastair Sharp, editing by G Crosse)