(Adds investor quotes and details throughout; updates prices)

* TSX falls 151.86 points, or 0.7%, to 20,925.49

* Materials group looses 1.7%; energy down nearly 2%

* Kinross Gold slides 10.2% as company makes acquisition

TORONTO, Dec 9 (Reuters) - Canada's main stock index fell on Thursday as investors took some profits following gains earlier in the week and weighed a more uncertain economic outlook due to the emergence of the Omicron variant.

The Toronto Stock Exchange's S&P/TSX composite index ended down 151.86 points, or 0.7%, at 20,925.49, its second straight decline following sharp gains on Monday and Tuesday. It is up 1.4% since the start of the week.

"It's quite natural to see this kind of volatility after a big surge like that," said Elvis Picardo, portfolio manager at Luft Financial, iA Private Wealth. "Investors in the market are trying to grapple with where we go next given that you've got this Omicron variant."

Increased restrictions in parts of the world to contain the spread of the new variant weighed on global equity markets.

"We are also seeing a combination of two things that are very seasonal - profit taking and tax-loss selling - so that's one of the reasons we are seeing volatility in specific sectors," Picardo said.

The materials group, which includes precious and base metals miners and fertilizer companies, lost 1.7% as the price of gold fell ahead of U.S. inflation data on Friday.

It was also weighed by a 10.2% drop in Kinross Gold Corp after the mining company said it would buy gold explorer Great Bear Resources Ltd for about C$1.8 billion ($1.4 billion).

Great Bear's shares jumped 25.1%.

The energy sector ended nearly 2% lower as oil prices fell on worries that measures by some governments to slow the spread of the Omicron coronavirus variant could hit demand.

U.S. crude oil futures settled nearly 2% lower at $70.94 a barrel.

Among other sectors, healthcare fell 3.6%, while technology was down 1.3%. (Reporting by Fergal Smith; Additional reporting by Susan Mathew and Anisha Sircar in Bengaluru Editing by Alistair Bell)