CALGARY -- Suncor Energy and Canadian Oil Sands have tentatively agreed to a merger valued at $6.6-billion based on Friday's stock price in one of the biggest deals the oilpatch has seen in recent years. Here's a quick look at the two companies:

Suncor Energy:

Founded in 1967, Suncor Energy has grown to become one of the largest energy companies in North America. At the end of 2014, it employed 13,980 people, though it has laid off about 1,200 workers since then.

Canadian Oil Sands:

The company began as the Canadian Oil Sands Trust in 1995. It has about 30 staff.

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Suncor Energy assets:

Suncor is Canada's dominant oilsands player, producing 430,300 barrels a day in the third quarter ended Sept. 30. That doesn't include its current 12 per cent Syncrude stake, which produced 28,100 barrels a day for Suncor in that quarter. The company also has four refineries and a network of about 1,500 Petro-Canada retail and wholesale outlets. It also operates the Terra Nova offshore platform in the North Atlantic. In recent years, it has diversified into clean energy projects, with seven wind power developments and a biofuels plant in Ontario.

Canadian Oil Sands assets:

The company has a 37 per cent share in Syncrude, its sole asset.

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Suncor Energy stock price:

Suncor's stock was trading at $29.98 on the TSX, down $1.24, just before 12 p.m. ET.

Canadian Oil Sands stock price:

Shares in COS were at $8.36 on the TSX, up $0.88, just before 12 p.m. ET.