(Updates to close, adds portfolio manager comment)
* TSX down 50.37 points, or 0.32 percent, to 15,854.77
* Seven of TSX's 10 main industry groups end lower
TORONTO, Oct 25 (Reuters) - Canada's benchmark stock index lost ground on Wednesday as disappointing quarterly results and apparel company Roots Corp's dismal trading debut helped set the tone for the broader market.
Canadian National Railway Co gave up all of the previous session's pre-earnings gains after it posted results that missed expectations. Canada's largest rail operator fell 1.1 percent to finish at C$104.26.
Air Canada, after opening higher following quarterly results that came in better than expected, ended 1.3 percent lower to C$26 as investors booked profits.
Industrial stocks as a whole fell 0.7 percent.
Roots' trading debut received a cool reception from investors wary about the uncertain retail industry. The stock tumbled 16.7 percent to C$10.
The Toronto Stock Exchange's S&P/TSX composite index fell 50.37 points, or 0.32 percent, to finish at 15,854.77.
Of the index's 10 main groups, seven sectors lost ground.
"The TSX it came within 50 points of an all-time high yesterday, but today there's been a little bit of a retreat," said Elvis Picardo, portfolio manager at HollisWealth in Vancouver.
"The markets are taking its cue from the U.S., where sentiment is being very much earnings driven. On the TSX specifically, the fact that Roots has had a lukewarm IPO hasn't really helped sentiment."
U.S. stocks slumped on Wednesday, with the Dow Industrials and S&P 500 suffering their worst day in seven weeks.
Enbridge Inc gave up 1.4 percent to end at C$48.63, as Credit Suisse cut its price target, while TransCanada Corp fell 1.9 percent to C$59.72. The company said earlier on Wednesday it was selling its Ontario solar assets for C$540 million.
Overall energy stocks see-sawed 0.1 percent lower alongside marginally cooler oil prices.
The heavily-weighted financial services sector fell 0.4 percent with Fairfax Financial Holdings Ltd sliding 2.3 percent to C$640.
Materials lost 0.3 percent, with Eldorado Gold slumping 11.6 percent to C$1.67. The miner extended this week's sharp plunge after reporting lower gold recoveries at its Kisladag mine.
On the upside, telecoms gained 1.0 percent with Telus Corp rising 3.0 percent to C$47.10.
On the economic front, the Bank of Canada held interest rates steady, as expected, and expressed caution as it considers future moves given the risks and uncertainties facing the economy.
Declining issues outnumbered advancing ones on the TSX by 139 to 104, for a 1.34-to-1 ratio on the downside.
Seventeen companies hit 52-week highs on the index, while eight touched new lows. (Reporting by Solarina Ho, editing by G Crosse)