* TSX rises 15.89 points, or 0.13 percent, to 12,453.92 * Five of 10 main sectors advance * Penn West jumps 5 percent after naming directors * Onex climbs after making takeover move By John Tilak TORONTO, May 6 (Reuters) - Canada's main stock index climbed for a third straight session on Monday as financial and industrial shares gained, and energy companies' stocks rallied after oil prices rose on Middle East tensions. A jump in Penn West Petroleum Ltd also supported the market after the oil and gas producer named two industry veterans to its board. But the market's gains were capped by weakness in the consumer staples sector. "You're seeing some appetite for risky assets," said Elvis Picardo, strategist and vice president of research at Global Securities in Vancouver. "You're seeing some money gravitate from the typically defensive sectors like the staples to slightly more cyclical names," he added. "Certainly the banks would be on the top of that list for anyone who is thinking of making that move." The Toronto Stock Exchange's S&P/TSX composite index gained 15.89 points, or 0.13 percent, to 12,453.92. Still, the benchmark index is barely up for the year, badly underperforming its record-breaking U.S. peers since the start of 2013. "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." Five of the index's 10 main sectors were higher. Shares of oil and gas companies were up 0.1 percent, helped by a rise in the price of Brent crude. Penn West jumped 5.1 percent to C$9.99 after the company named former Suncor Energy Inc CEO Rick George and former Canadian Natural Resources Ltd Chairman Allan Markin to its board. Financials, the index's most heavily weighted sector, rose 0.3 percent, and industrials added 0.7 percent. But consumer staples fell 0.8 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 0.4 percent to C$49.80.