Here is the reason for the 662/3 percent vote required.

The acquisition of a Canadian public
company is regulated under:
» Corporate Statutes. Canadian corporations
may be incorporated under
a federal, provincial or territorial
statute. These statutes regulate certain corporate
transactions (including statutory amalgamations
and plans of arrangement) and other extraordinary
transactions (including the sale, lease or
exchange of all or substantially all of the property
of a corporation, liquidation and dissolution).
Most statutes require that these transactions be
approved by a special resolution of shareholders
(662/3% of the votes cast) and give shareholders
rights to dissent and demand fair value for the
shares held by them. Canadian courts have broad
remedial powers under these statutes to intervene
in respect of transactions that are oppressive or
unfairly prejudicial to or that unfairly disregard
shareholder interests.