* TSX closes up 15.22 points, or 0.1 percent, at 15,143.87
* Financials gain 0.4 percent; materials rise 0.3 percent
* Index loses 0.3 percent for the month
* Just four of TSX's 10 main groups end higher
By Fergal Smith
TORONTO, July 31 (Reuters) - Canada's main stock index edged up on Monday as higher bond yields supported financial shares and base metal miners got a boost from a 2-year peak for copper prices, but the TSX still lost ground for the third straight month.
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE closed up 15.22 points, or 0.1 percent, at 15,143.87. For the month, the index lost 0.3 percent.
"It is not out of the ordinary to see this kind of move into the last day of the month," said Mike Archibald, associate portfolio manager at AGF Investments. "As guys are putting more cash to work, they tend to do it in large liquid names."
The heavily weighted financials group rose 0.4 percent, helped by gains for some of the country's major banks and insurance companies after the yield on Canada's 10-year bond reached its highest intraday level since November 2014, at 2.071 percent.
Higher bond yields increase net interest margins of banks and reduce the value of insurance companies' liabilities.
Adding to support for insurance companies are investor expectations for solid earnings, Archibald said.
Manulife Financial Corp MFC.TO rose 0.9 percent to C$25.68 and Sun Life Financial Inc SLF.TO gained 0.3 percent to C$47.78. Both insurers are due to report earnings on Aug. 9.
The materials group, which includes precious and base metals miners and fertilizer companies, added 0.3 percent.
Copper prices were at a two-year peak, boosted by a Chinese government-led infrastructure push that kept construction humming in the world's second-largest economy. Quantum Mineral Ltd FM.TO climbed 2.4 percent to C$13.78 and Teck Resources Ltd TECKb.TO rose 2.7 percent to C$27.06.
Gold miners were more mixed, however, with several slipping even as the price of bullion reached its highest in nearly seven weeks on a struggling U.S. dollar. Gold Corp ELD.TO fell 5.7 percent to C$2.64, hitting its lowest since 2005, as several analysts cut their recommendations and price targets on the stock following disappointing earnings on Friday.
B2Gold Corp BTO.TO fell 6.9 percent to C$3.13.
Just four of the index's 10 main groups ended higher.
The energy group was the biggest drag, falling 0.6 percent despite higher oil prices.
Precision Drilling Corp PD.TO fell nearly 4 percent to C$3.62 even after reporting a smaller-than-expected quarterly loss. crude CLc1 prices were up 1.0 percent at $50.18 a barrel as news of a producers' meeting next week added to bullish sentiment.