(Adds details, updates prices) Aug 9 (Reuters) - Canada’s main stock index fell from record highs on Monday, with the heavyweight energy sector leading losses as rising COVID-19 cases stoked concerns over crude demand, driving oil prices 4% lower. * At 9:40 a.m. ET (13:40 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 94.4 points, or 0.46%, at 20,381.02. * The energy sector dropped 1.9% as oil prices plummeted on concerns that rising COVID-19 cases, particularly in major importer China, could lead to new restrictions and dent fuel demand. * The materials sector, which includes precious and base metals miners and fertilizer companies, lost 1% as concerns over Chinese demand hit base metal prices, while a rising dollar hurt precious metals. * Defensive sectors such as real estate and consumer staples were among the few gainers. * The financials sector slipped 0.3%. The industrials sector fell 0.1%. * On the TSX, 50 issues advanced, while 178 issues declined in a 3.56-to-1 ratio favoring losers, with 19.35 million shares traded. * The largest percentage gainer on the TSX was WPT Industrial Real Estate Investment Trust, which jumped 15.1% after private equity firm Blackstone agreed to buy the company for $1.86 billion. * Westport Fuel fell 7.0%, the most on the TSX, while the second biggest decliner was Lightspeed Pos Inc , down 6.3%. * The most heavily traded shares by volume were Enbridge Inc , Manulife Financial and Bombardier Inc . * The TSX posted four new 52-week highs and three new lows. * Across Canadian issues, there were 48 new 52-week highs and 11 new lows, with total volume of 34.68 million shares. Reporting by Ambar Warrick; editing by Subhranshu Sahu and Vinay Dwivedi Our Standards: The Thomson Reuters Trust Principles.