(Updates prices, sectors) June 28 (Reuters) - Canada’s main stock index erased early gains on Monday, slipping from an all-time high, as a sharp drop in energy shares on lower crude prices offset gains in technology stocks. * The energy sector tumbled 2.5% as U.S. crude prices fell 0.6% a barrel, while Brent crude lost 0.6%. * The tech subindex, on the other hand, rose over 1%, tracking gains in the Nasdaq. * At 9:42 a.m. ET (13:42 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 25.41 points, or 0.13%, at 20,204.85, after hitting a record high of 20,273.6 in early trade. * The financials sector slipped 0.6%, while the industrials sector fell 0.3%. * The materials sector, which includes precious and base metals miners and fertilizer companies, rose 0.1%. * On the TSX, 97 issues were higher, while 128 issues declined for a 1.32-to-1 ratio to the downside, with a total volume of 13.24 million shares. * Electric utility Brookfield Renewable Partners L.P. was the top gainer, jumping 3.2%, after Credit Suisse upgraded it to “outperform” from “neutral”, followed by a 2.8 rise by e-commerce firm Shopify Inc, after Barclay raised its price target. * Sandstorm Gold Ltd fell 5.8%, the biggest decline on the TSX, after brokerage RBC downgraded the rating of the gold miner. * The second biggest decliner was oil producer Vermilion Energy Inc, down 3.5%. * The most heavily traded shares by volume were Bombardier Inc, Athabasca Oil Corp and Nevada Copper Corp, respectively. * The TSX posted six new 52-week highs and three new lows. * Across all Canadian issues there were 82 new 52-week highs and 15 new lows, with total volume of 33.42 million shares. (Reporting by Amal S in Bengaluru; Editing by Rashmi Aich) Our Standards: The Thomson Reuters Trust Principles.