Is this a US thing? 2/3 . . I didn't understand this either .... Does the 51% not being seen to be attainable? I have no idea . . . Maybe a 2/3 is a very conclusive "stand" - 51% is somehow . .. weak!

2/3 or 3/4 majorities (called "supermajorities") are a pretty common tactic in U.S. voting (both government and corporate) for major, irreversible decisions. For example, Congress and most state legislatures can override a Presidential or Gubernatorial veto of legislation only with a 2/3 vote. Constitutional amendments are another category that requires a supermajority. The idea is that the added burden of getting a supermajority forces opposing sides to compromise or to seek more innovative solutions that will keep a larger number of people happy.

It seems reasonable to me that if a company is voting to sell off the product line that started the corporation to begin with, that the by-laws might require some kind of supermajority. Otherwise, if 49% of the shareholders are bitterly opposed to the deal, they might decide to dump stock if the deal goes through over their objections.