(Adds analyst quotes and details on background and Hudson's Bay and updates prices)
* TSX closes down 165.21 points, or 1.06 percent, at 15,379.61
* Index touches its lowest since Dec. 30
* Nine of the TSX's 10 main groups end lower
TORONTO, March 14 (Reuters) - Canada's main stock index tumbled on Tuesday to its lowest this year as declining oil prices weighed on the energy sector, while Valeant Pharmaceuticals International Inc plunged on the exit of an activist investor.
Losses for the Toronto Stock Exchange's S&P/TSX composite index came as global investors tread cautiously ahead of a widely expected interest rate hike from the Federal Reserve on Wednesday.
"We are seeing markets around the world roll over," said Colin Cieszynski, senior market analyst at CMC Markets Canada.
"We are just at the point where we have reached exhaustion. We had just a massive screaming rally for several months and now people are waiting for more details (on proposed U.S. economic stimulus)."
Investors have been betting that U.S. President Donald Trump will cut corporate taxes, spend on infrastructure and deregulate banks.
"He has been big on the broad strokes ... but now 'the street' is starting to run out of patience," Cieszynski said.
The energy group retreated 1.6 percent, taking losses since the start of the year to 12 percent, as oil prices fell to three-month lows after OPEC reported a rise in global crude stocks and a surprise output jump from its biggest member, Saudi Arabia.
Oil pipeline operators were among the biggest drags, with Enbridge Inc falling 1.8 percent to C$54.38.
Valeant slumped nearly 10 percent to C$14.59 after billionaire investor William Ackman walked away from the struggling drug company after trying to rescue it for some 18 months, taking a loss of more than $3 billion.
The TSX closed down 165.21 points, or 1.06 percent, at 15,379.61, its lowest close since Dec. 30. The index also hit its lowest intraday since Dec. 30 at 15,370.90.
Convenience store operator Alimentation Couche Tard Inc fell 4.8 percent to C$58.85 after reporting earnings that missed analyst estimates.
Hudson's Bay Co is in exploratory talks about acquiring Neiman Marcus, according to people familiar with the matter. Its shares fell 1.2 percent to C$11.75.
Nine of the index's 10 main groups ended lower.
The materials group, which includes precious and base metals miners and fertilizer companies, lost 2.4 percent and financials retreated 0.4 percent. Industrials declined 1.2 percent as railroad stocks lost ground.
Gold futures fell 0.4 percent to $1,198 an ounce, while copper prices advanced 0.4 percent to $5,820.15 a tonne.
U.S. crude oil futures settled 68 cents lower at $47.72 a barrel. (Additional reporting by Alastair Sharp; Editing by Bill Trott and James Dalgleish)