Last week Ensign raised its $2.30 per share bid to $2.60, and lifted its bid for the options to $1.40 from $1.10 per option. Rival bidder Parker Drilling said it would not be raising its $2.50 bid any higher.

The board of AOG has recommended that shareholders accept the latest offer. "The Ensign offer prices are now within (and potentially above) the valuation range considered by the Independent Expert to be fair and reasonable," the company said in a statement today.