* TSX down 52.07 points, or 0.34 percent, to 15,390.68
* All 10 of the TSX's main groups fall
By Solarina Ho
TORONTO, June 5 (Reuters) - Canada's main stock index fell on Monday as financial stocks dipped amid signs of cooling in Toronto's overheated housing market and falling oil prices, weakened by concerns of a diplomatic rift in the Middle East, hurt energy stocks.
At 11:08 a.m. ET (1508 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 52.07 points, or 0.34 percent, to 15,390.68, after sliding as much as 97.81 points to 15,344.94 in earlier trading and then briefly turning positive.
All 10 of the index's main groups lost ground.
Healthcare was the biggest decliner, with Valeant Pharmaceuticals Inc falling 4.4 percent to C$16.15. The sector was down 2 percent.
Energy stocks, which briefly reversed course mid-morning, retreated again, and were down 0.4 percent, with Cenovus Energy falling 1.6 percent to C$11.42.
Top crude exporter Saudi Arabia, along with other countries in the region, cut ties with Qatar, accusing it of undermining regional stability. Uncertainty over the impact saw crude prices rise initially before changing course on worries it could hurt a global deal to scale back oil production.
Financials, which also swung into positive territory briefly, eased 0.1 percent. Individual stock moves were modest, but the group accounts for a third of the index.
Data showed housing sales in Toronto fell sharply in May, while new listings jumped, as sellers looked to cash in on high prices and buyers moved to the sidelines in the wake of new housing rules aimed at cooling demand. Prices continued to rise, but below the pace of recent gains.
Financial have swung back and forth in recent weeks as investors wavered between concerns over the housing market and robust earnings from Canada's biggest banks and healthy quarterly gross domestic product growth.
"As long as growth continues to be relatively strong throughout the rest of the year, I think there's better value in the TSX versus the S&P," said Bryden Teich, portfolio manager at Avenue Investment Management.
Osisko Gold Royalties Ltd rose 9.7 percent to C$15.79 after news it will buy a precious metals portfolio from Orion Mine for C$1.13 billion.
Asanko Gold Inc declined 0.5 percent to C$2.11 after it said its liquidity position was likely to be over $100 million by mid-2018, days after short seller Muddy Waters said the Canadian gold miner would run out of cash by next year.
The materials group, which includes precious and base metals miners and fertilizer companies, lost 0.7 percent. (Reporting by Solarina Ho; Editing by James Dalgleish)