(Adds portfolio manager quotes, background; updates prices)
* TSX ends down 31.23 points, or 0.21 percent, at 15,182.19
* Six of index's 10 main sector groups end lower
* Index falls 1.1 pct in June, down 0.9 pct on week
By Fergal Smith
TORONTO, June 30 (Reuters) - Canada's benchmark stock index fell on Friday, ending lower for the second month in a row, as heavyweight financial and energy shares lost ground ahead of a holiday weekend.
The Toronto Stock Exchange's S&P/TSX composite index closed down 31.23 points, or 0.21 percent, at 15,182.19. For the week, the index lost 0.9 percent, while it ended 1.1 percent lower for the month.
"A lot of people don't like to be long over the weekend, let alone long over four days," said John Kinsey, portfolio manager at Caldwell Securities.
The Canadian stock market will be closed on Monday for Canada Day, while some investors could stay away from their desks on Tuesday as Wall Street closes for the U.S. Independence Day holiday.
"We may be into the summer doldrums a little early," Kinsey said.
Some of the most influential movers on the index were its biggest banks and insurers, with Royal Bank of Canada down 0.6 percent at C$94.16 and Manulife Financial Corp off 0.7 percent at C$24.31.
The financials group, which accounts for a third of the index's weight, lost 0.4 percent.
Exploration stage uranium company Nexgen Energy Ltd advanced 8.7 percent to C$2.87 after saying it had secured $110 million in financing.
But Cameco Corp, a larger uranium producer, shed 3.8 percent to C$11.81. Bank of America analysts wrote in a research note that oversupply in the uranium market would likely weigh on Cameco's stock for several years.
The broader energy group fell 0.5 percent even as oil climbed for a seventh straight session, boosted by decrease in the U.S. rig count and stronger demand data from China.
Six of the index's 10 main industry groups ended lower.
The materials group, which includes precious and base metals miners and fertilizer companies, added 0.2 percent, while the consumer discretionary sector rose 0.5 percent as Canada's economy showed signs of strength.
Restaurant Brands International Inc, which operates the Tim Hortons and Burger King franchise restaurants, rose 0.9 percent to C$81.14 and global automotive supplier Magna International Inc climbed 1.1 percent to C$60.07.
Canada's economy grew for a sixth consecutive month in April, while a central bank survey of business sentiment showed firms were feeling more upbeat.
Top Bank of Canada officials' recent assertions that a pair of 2015 interest rate cuts did their job in cushioning the economy from collapsing oil prices appear to be paving the way for a tightening move as soon as next month. (Additional reporting by Alastair Sharp, editing by G Crosse)