(Updates prices, sectors) April 14 (Reuters) - Canada’s main stock index gained on Wednesday as investors expect substantial fiscal stimulus measures to be announced next week, while a jump in oil prices supported the commodities-heavy index. Canada’s Liberal government will deliver on its promise to spend big when it presents its first budget in two years next week amid a fast-rising third wave of COVID-19 infections and ahead of an election expected in the coming months. * At 9:38 a.m. ET (13:38 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was up 83.86 points, or 0.44%, at 19,287.56. * The energy sector climbed 1.8% as U.S. crude prices were up 2.1% a barrel, while Brent crude added 2.2%. * The financials sector gained 0.3% and the industrials sector rose 0.4%. * The materials sector, which includes precious and base metals miners and fertilizer companies, added 0.5%. Gold futures remained unchanged at $1,745.9 an ounce. * On the TSX, 150 issues advanced, while 70 issues declined in a 2.14-to-1 ratio favoring gainers, with 13.54 million shares traded. * The largest percentage gainers on the TSX were Denison Mines Corp, which jumped 4.5%, and Lithium Americas , which rose 3.9%. * OrganiGram Holding fell 7.1%, the most on the TSX, while the second biggest decliner was Badger Daylighting , down 3.0%. * The most heavily traded shares by volume were Toronto-Dominion Bank, Royal Bank of Canada and The Supreme Cannabis Company. * The TSX posted 12 new 52-week highs and no new low. * Across Canadian issues, there were 89 new 52-week highs and two new lows, with total volume of 25.64 million shares. (Reporting by Shashank Nayar in Bengaluru; Editing by Shinjini Ganguli and Vinay Dwivedi)