When a poison pill defence is triggered, shareholders can buy stock in the target company at a discount, making the shares less attractive to a hostile buyer.
The plan is meant to buy COS more time to weigh Suncor's all-stock offer of $4.3 billion — open until Dec. 4 — as well as any alternatives.
Suncor approached COS twice in March and April in the hopes of inking a friendly takeover deal, but the would-be target's board rejected those advance's unanimously.
The current offer is worth substantially less than the earlier overtures — $8.84 a share versus $11.84 as of March 31.
If Suncor — already the dominant oilsands producer — is successful in taking over COS, it would own just under half of the massive Syncrude Canada mine north of Fort McMurray, Alta.
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