There's a bit of a feedback mechanism, since the only price that really matters is the one you can get. If you had an auction (the stock market is already an auction that's always ongoing, btw) as soon as its revealed that Warren Buffet bid X, you'll see people bid X+1, even if 30 seconds earlier they had scoffed that X was totally unrealistic. You could have a silent auction, but the facts come out eventually, and then you'll see the same eruption of trading. That's almost what the bankers are doing behind the scenes, holding a private silent auction.