A = the lowest value that someone is willing to sell a share at right now, multiplied by the number of shares that exist. B = the sum over all shares of the pr

A = the lowest value that someone is willing to sell a share at right now, multiplied by the number of shares that exist. B = the sum over all shares of the price that each share's owner is willing to sell it for right now. B > A, by definition. This is why buyouts typically happen at a premium above the share price, because a flat out purchase of shares on the open market would send the price through the roof. So the buyout price is set at a level where enough people feel like they're getting a good deal to let the deal can go through without stirring up too much shit. tl;dr market cap doesn't mean very much, and shouldn't be compared to a buyout offer, at least without some adjustment.