And who is arguing that they are perfectly efficient? Markets work on information, which is not (initially) evenly distributed and because of the physics can only spread at the speed of light once it is known.
> Since markets are not super efficient, basic exposure to performance factors (small cap, value, momentum...) puts you at a fairly high likelyhood of beating SPX.
Two of the proponents efficient markets explain why (and shared a Nobel for the work):
And who is arguing that they are perfectly efficient? Markets work on information, which is not (initially) evenly distributed and because of the physics can only spread at the speed of light once it is known.
The latter was used to detect insider trading:
* https://www.npr.org/sections/alltechconsidered/2013/09/24/22...
For the former, people are renting satellite time to get to information that no one else has to determine trades:
* https://newsroom.haas.berkeley.edu/how-hedge-funds-use-satel...
> Since markets are not super efficient, basic exposure to performance factors (small cap, value, momentum...) puts you at a fairly high likelyhood of beating SPX.
Two of the proponents efficient markets explain why (and shared a Nobel for the work):
* https://en.wikipedia.org/wiki/Fama–French_three-factor_model
The two are not mutually exclusive, and there is published literature on it.
Good interview with Fama (audio, video, transcript):
* https://rationalreminder.ca/podcast/200