Only under efficient market hypothesis (EMH), which is not necessarily the true state of the market. Under EMH, 2008 would never have happened, because all the

Only under efficient market hypothesis (EMH), which is not necessarily the true state of the market. Under EMH, 2008 would never have happened, because all the (unforeseen) risk would have been priced in as 'knowable' - the risk of default was mathematically provable, even if no one ever took the time to do the math.