(Updates prices, sectors) July 26 (Reuters) - Canada’s main stock index fell on Monday, erasing initial gains at the open, as weakness in technology stocks offset gains in commodity-related shares. * The technology sector fell 1.34% after touching a record high on Friday, with tech stocks including Shopify Inc and Blackberry Ltd among the top drags. * At 9:45 a.m. ET (1345 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 38.71 points, or 0.19%, at 20,149.72. * The energy sector climbed 0.9% as crude prices were steady as the spread of the COVID-19 Delta variant stoked fears over future fuel demand, but supply looked set to be tight through the rest of the year. * The materials sector, which includes precious and base metals miners and fertilizer companies, added 1%. * The financials sector slipped 0.1%. The industrials sector fell 0.6%. * On the TSX, 102 issues were higher, while 126 issues declined for a 1.24-to-1 ratio to the downside, with 16.75 million shares traded. * Biotech firm Trillium Therapeutics Inc fell 4.2%, the most on the TSX, and the second biggest decliner was marine port service provider Westshore Terminals Investment Corp , down 3.6%. * The largest percentage gainer on the TSX was lithium miner Lithium Americas Corp, which jumped 7.0% on positive ruling on Nevada mine site. * Its gains were followed by miner Teck Resources Ltd , which rose 4.3%. * The most heavily traded shares by volume were Royal Bank of Canada, Bank of Montreal and Harte Gold Corp . * The TSX posted no new 52-week highs and no new lows. * Across all Canadian issues there were 44 new 52-week highs and four new lows, with total volume of 31.46 million shares. (Reporting by Amal S in Bengaluru; Editing by Shailesh Kuber) Our Standards: The Thomson Reuters Trust Principles.