* Trade tensions were triggered by President Donald Trump, who warned China on Tuesday against waiting out his first term in office to finalize any trade deal, saying if he wins re-election in the November 2020 US presidential contest, the outcome could be no agreement or a worse one.

* Traders awaited signals on whether the US central bank will offer an insurance rate-cut to combat risks from ongoing trade tensions or is prepared to lower borrowing costs a number of times in anticipation of an economic downturn.

* The Federal Reserve will release its policy statement at 2 p.m. EDT (1800 GMT) on Wednesday, and Fed Chair Jerome Powell will hold a press conference shortly after.

* The energy sector dropped 0.7%, the most among the 10 major sectors trading lower.

* The materials sector, which includes precious and base metals miners and fertilizer companies, added 0.9% as gold futures rose 0.6% to $1,428.6 an ounce.

* At 9:48 a.m. ET (1348 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 40.15 points, or 0.24%, at 16,452.02.

* On the TSX, 79 issues were higher, while 145 issues declined for a 1.84-to-1 ratio to the downside, with 18.08 million shares traded.

* The largest percentage gainer on the TSX was Nutrien Ltd , which jumped 5.1% after reporting quarterly results.

* Cannabis producer Aphria Inc rose 2.4% and was among the top gainers on the main index.

* Colliers International Group fell 6.6%, the most on the TSX, after the company's quarterly results missed estimates.

* The second-biggest decliner was First Quantum Minerals Ltd , down 2.9%, after reporting second-quarter revenue that missed expectations.

* The most heavily traded shares by volume were Aurora Cannabis, Royal Nickel, and Hexo Corp .

* The TSX posted ten new 52-week highs and eight new lows.

* Across all Canadian issues, there were 23 new 52-week highs and 16 new lows, with total volume of 29.01 million shares.