It’s worth noting that efficient markets are a modeling assumption to make certain economic problems computationally tractable and easy to model. It’s not a law of nature confirmed by observation. On the contrary a lot of times markets are observed to be inefficient (eg the housing market mid 2000s or at a higher level of sophistication the mortgage backed securities market in the same period).
Even very liquid markets like the FX market with technically sophiscated arbitrage free pricing models still have had long running well known ineffiencies like the forward rate bias.
That’s fair enouph. So long as it is remembered that it’s a heuristic and is used to guide thinking rather than stop thinking it is certianly valuable.
Corollary: if you want to find investments with significantly higher than average expected values, look for structural reasons that a market might be inefficient, or reasons that many smart players might be making the same evaluation mistake.
Note that actually following the above as advice might be extremely hazardous: taken in a different light, it feels a lot like the advice “seek out confirmation bias”.
It’s worth noting that efficient markets are a modeling assumption to make certain economic problems computationally tractable and easy to model. It’s not a law of nature confirmed by observation. On the contrary a lot of times markets are observed to be inefficient (eg the housing market mid 2000s or at a higher level of sophistication the mortgage backed securities market in the same period).
Even very liquid markets like the FX market with technically sophiscated arbitrage free pricing models still have had long running well known ineffiencies like the forward rate bias.
Sure, but they are still a useful heuristic.
That’s fair enouph. So long as it is remembered that it’s a heuristic and is used to guide thinking rather than stop thinking it is certianly valuable.
Corollary: if you want to find investments with significantly higher than average expected values, look for structural reasons that a market might be inefficient, or reasons that many smart players might be making the same evaluation mistake.
Note that actually following the above as advice might be extremely hazardous: taken in a different light, it feels a lot like the advice “seek out confirmation bias”.