Updates throughout, adds details and analyst comments

By Nikhil Sharma

Feb 5 (Reuters) - Canada's main stock index fell on Thursday as sharp declines in precious metals pressured mining stocks, while investors assessed a new batch of Wall Street tech earnings and weighed Alphabet's ambitious spending plans.

At 9:52 a.m. ET, the S&P/TSX composite index .GSPTSE was down 0.6% at 32,376.76 points - on track to snap a three-day streak of gains.

The broader materials index .GSPTTMT tumbled 2.9% as gold and silver prices tanked against a stronger dollar and amid signs of easing geopolitical tensions.

Spot gold XAU= fell 2% and spot silver XAG= sank 12.7%, with the top white metal miners bearing the brunt.

First Majestic Silver AG.TO and Silvercorp Metals SVM.TO were down 4.1% and 5.1%, respectively, while Pan American Silver PAAS.TO lost 4.5%.

Barrick Mining ABX.TO tumbled 4.5% in the selloff, despite beating fourth-quarter profit estimates.

Recent swings in commodity markets have increased volatility in Toronto's resource-heavy benchmark index, leaving investors in uncertainty and highlighting the Canadian markets' sensitivity to global geopolitical unrest.

"Anytime there's volatility, it's going to cause investors to be nervous," said Allan Small, senior investment advisor at Allan Small Financial Group with iA Private Wealth.

"It makes them more nervous perhaps than even they should be because there's a lot of noise and everybody focuses on all the noise and sometimes they are very dramatic. They overdo it. It's not as bad as the situation is dictating."

A key contributor to the TSX's moves was also Wall Street, where the benchmark S&P 500 index .SPX fell 0.7% as investors digested quarterly earnings from the so-called "Magnificent Seven" constituent, Alphabet GOOGL.O.

While the tech giant posted robust results, its increased capital spending target spooked investors, sending the stock down 3.4%.

Meanwhile, Canada Goose GOOS.TO missed analysts' estimates for third-quarter profit, hurt by an increase in marketing and promotional spending, sending the luxury apparel maker's shares 15.4% down in early trading.

Thomson Reuters TRI.TO lost 4.3% despite reporting higher fourth-quarter revenue.

(Reporting by Nikhil Sharma; Editing by Shreya Biswas)

((Nikhil.Sharma@thomsonreuters.com;))