bill ackman on why large, boring companies now drop 25% in a day, something he says almost never happened when he started: "a quarter of every american business, plus or minus, is owned by some combination of vanguard, state street and northern trust. when you shrink the float of a public company, the marginal buyer and seller is going to have more impact on the stock price." "the marginal buyer and seller today is a citadel or a millennium. they operate with a large amount of leverage, very large gross books, and they're increasingly short-term." "most investors are very short-term focused because they're compensated that way. they won't invest in a company unless they're confident the price is going to be higher on december 31st." passive owns the float, pods set the price, and both are structurally unable to hold through a bad quarter. that inability is the opportunity.