Canada's main stock index dipped on Wednesday ahead of a crucial interest rate decision from the US Federal Reserve.

* The US Federal Reserve is almost certain to cut interest rates by at least quarter-percentage-point for the first time in more than a decade on Wednesday, delivering a mild jolt to an economy that is facing headwinds from trade disputes.

* The central bank is scheduled to release its rates decision at 2 p.m. ET (1800 GMT) at the end of a two-day policy meeting.

* A bright spot was data that showed Canada's economy grew by a higher-than-expected 0.2% in May, the third increase in as many months, thanks to a rebound in manufacturing.

* Brian DePratto, a senior economist with TD Economics, noted the current economic backdrop "should give the Bank of Canada some near-term comfort in 'going it alone' and holding its stance of monetary policy constant as its peers ease."

* At 9:45 a.m. ET (13:45 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 16.02 points, or 0.1%, at 16,450.03.

* The energy sector climbed 0.8%, as US crude prices were up 0.8% a barrel, while Brent crude added 0.7%.

* On the TSX, 106 issues were higher, while 122 issues declined for a 1.15-to-1 ratio to the downside, with 18.69 million shares traded.

* The largest percentage gainers on the TSX were Seven Generations Energy Ltd, which jumped 14.6% after reporting second-quarter results.

* Home Capital Group Inc, which rose 9.6%, was among the top percentage gainers on the main index.

* Overnight air cargo services Cargojet fell 5.7%, the most on the TSX, while the second-biggest decliner was Intact Financial Corp, down 4.0%, after they reported quarterly results.

* The most heavily traded shares by volume were Encana Corp , MEG Energy Corp and Northern Dynasty Minerals .

* The TSX posted nine new 52-week highs and no new low.

* Across all Canadian issues, there were 21 new 52-week highs and six new lows, with total volume of 30.01 million shares.