TORONTO (Reuters) - Toronto's main stock index ended lower yesterday as a decision by Canada to allow upstart Globalive to offer wireless service opened up competition in the telecoms sector and dragged down shares of existing mobile carriers.

Rogers Communications Inc, Canada's biggest wireless firm, was the No. 1 heavyweight loser of the day, falling 6.95 percent to C$31.05. Rival BCE Inc fell 2.39 percent to C$27.35, and Telus Corp dropped 2.3 percent to C$32.90.

Canada surprised investors yesterday by allowing Egyptian-backed Globalive to offer wireless phone service, overturning a regulatory ruling and setting the stage for stepped-up competition in the sector.

"I think that the Globalive news has come as a bit of shock to the telecommunications sector on the whole, but Rogers has been the worst hit because it's largely dependent on the wireless business for its revenues," said Elvis Picardo, analyst and strategist at Global Securities in Vancouver. The S&P/TSX composite index ended down 40.64 points, or 0.35 percent, at 11,423.93. For the week, it ended down 0.75 percent.

"We've seen some profit-taking in recent weeks in the commodities sectors and gold, so that may be one of the reasons for the sustained weakness on the TSX in the last while," said Picardo.

The gold-mining sector was another big drag on the market Friday. Barrick Gold dropped 2.76 percent to C$41.90 and Goldcorp slid 1.49 percent to C$42.29. The price of gold hit a four-week low in response to upbeat US economic data that strengthened the US dollar and diminished gold's appeal as an inflation hedge.

"Gold on the week has given up about $66," said John Ing, president of Maison Placements Canada. He said profit-taking was likely also to have played into the selloff in gold mining stocks.

"My sense is that both the intermediate and long-term direction is still up (for gold)," he said.