Black-Scholes is a know-nothing system. If you know nothing about value - only price - then Black-Scholes is a pretty good guess at what a 90-day option might be worth. But the minute you get into longer periods of time, it's crazy to get into Black-Scholes. For example, at Costco we issued stock options with strike prices of $30 and $60, and Black-Scholes valued the $60 ones higher. This is insane.
Charlie MungerI have a name for people who went to the extreme efficient market theory-which is "bonkers". It was an intellectually consistent theory that enabled them to do pretty mathematics. So I understand its seductiveness to people with large mathematical gifts. It just had a difficulty in that the fundamental assumption did not tie properly to reality.
Charlie MungerA banker who is allowed to borrow money at X and loan it out at X plus Y will just go crazy and do too much of it if the civilization doesn't have rules that prevent it.
Charlie Munger