(Adds investment advisor comment, updates prices to close)
* TSX ends down 50.01 points, or 0.33 percent, at 14,897.50
* Six of the TSX's 10 main groups decline
By Alastair Sharp
TORONTO, June 25 (Reuters) - Canada's main stock index finished lower on Thursday, pulled down by a hefty retreat in energy names that snapped a three-session rally.
The Toronto Stock Exchange's S&P/TSX composite index ended down 50.01 points, or 0.33 percent, at 14,897.5.
Suncor Energy Inc fell 3.2 percent to C$34.56, while Encana Corp declined 3.4 percent to C$14.24 and Canadian Natural Resources lost 2.1 percent to C$35.13.
The overall group retreated 1.7 percent, hurt by oil prices that were pulled lower by uncertainties over a solution to Greece's debt crisis and the potential easing of sanctions on crude-producing Iran.
"The hope is that now oil has dropped significantly and will stay at this level or even fall further over time, that other sectors like, for one, manufacturing will pick up the slack," said Allan Small, a senior investment advisor at Dundee Wealth.
"If you're not in the oil sector, a low price for oil is going to help you," he said.
Telecom stocks moved 0.5 percent higher overall, with BCE Inc adding 0.9 percent to C$54.50 after announcing a broadband expansion plan. Shaw Communications Inc rose 0.5 percent to C$27.83 despite posting disappointing quarterly results.
Losses outside of the energy group were modest, with many investors awaiting resolution to Greece's debt situation.
"Clearly the biggest concerns out there include Greece. It's very psychological at this point. It's testing Europe, testing central bankers. People don't know what the effects will be," said Irwin Michael, portfolio manager at ABC Funds.
The materials group, home to mining companies, slipped 0.3 percent, with First Quantum Minerals Ltd falling 4.7 percent to C$17.28. Teck Resources Ltd shed 5.7 percent to $13.13.
Decliners outnumbered advancers by 156 to 88, for a 1.77-to-1 ratio on the downside. (Additional reporting by Solarina Ho; Editing by Meredith Mazzilli and James Dalgleish)