The Toronto stock market looked set for a modest gain at the open Wednesday amid rising oil prices, mixed earnings reports and major acquisition activity in the oilpatch.

Canadian affiliates of U.S. energy giant Exxon Mobil Corp. (NYSE:XOM) have agreed to buy Celtic Exploration Ltd. of Calgary (TSX:CLT) in a transaction valued at $3.1 billion, including assumed debt and spending obligations.

Celtic's shareholders are being offered $24.50 per share and a half-share of a new company, code-named Spinco, in return for each share. Celtic's stock closed Tuesday at $18.12 on the Toronto Stock Exchange before the announcement.

Also in Canada's energy sector, Penn West Petroleum Ltd. (TSX:PWT) has agreed in principle to sell $1.3-billion worth of its non-core properties, representing the equivalent of 12,000 barrels per day of production. Details weren't disclosed.

The Canadian dollar was up 0.25 or a cent to 101.59 cents US.

The loonie fell 0.7 of a cent Tuesday in the wake of a speech by Bank of Canada governor Mark Carney, which traders interpreted as containing a tone toward the possibility of hiking rates.

The bank makes its next announcement on interest rates next Tuesday.

U.S. futures were mixed with the Dow Jones industrial futures ahead 10 points to 13,463, the Nasdaq futures dipped 1.75 points to 2,763.5 and the S&P 500 futures ran ahead 3.3 points to 1,452.5.