* TSX rises 46.97 points, or 0.38 percent, to 12,485 * Nine of the 10 main index sectors advance * Penn West jumps after naming directors * Onex climbs after making takeover move By John Tilak TORONTO, May 6 (Reuters) - Canada's main stock index advanced for a third straight session on Monday, led by stronger financial shares and by gains in resource companies after some commodity prices rose. A jump in Penn West Petroleum Ltd also supported the market after the oil and gas producer named two industry veterans to its board. The Toronto benchmark index was outperforming its U.S. peers on Monday, a contrast to its showing since the start of the year. "Things will get better in Canadian equity markets" as the year progresses, said Arthur Salzer, executive director and chief executive at Northland Wealth Management. "We really haven't done much in the last five to six months, and we think there will be slightly better times ahead." The Toronto Stock Exchange's S&P/TSX composite index was up 46.97 points, or 0.38 percent, at 12,485. Nine of the 10 main sectors on the index were higher. Shares of oil and gas companies were up 0.5 percent, helped by a rise in the price of Brent crude. Penn West jumped 6.8 percent to C$10.16 after the company named former Suncor Energy Inc CEO Rick George and former Canadian Natural Resources Ltd Chairman Allan Markin to its board. The index's materials sector, which includes mining stocks, climbed 0.4 percent. Gold miners, which have had a disastrous run this year, were up 0.5 percent as bullion prices rose. "We've probably seen the worst in the gold sector," Salzer said. "The latter part for the year will be stronger because the golds will start to get attention again." Financials, the index's most heavily weighted sector, rose 0.5 percent. Shares of private equity firm Onex Corp were up after it said it would buy market research company Nielsen Holdings NV's expositions business for $950 million in cash. Onex shares climbed 0.6 percent to C$49.89.