Inexploitability is not efficiency. Back in the 2000s, plenty of financiers knew the subprime market was overpricing assets for years before anyone figured out

Inexploitability is not efficiency. Back in the 2000s, plenty of financiers knew the subprime market was overpricing assets for years before anyone figured out how to profitably short the market. Hard to deflate asset-price bubbles are a fact of finance. https://en.wikipedia.org/wiki/The_Big_Short https://en.wikipedia.org/wiki/The_Big_Short