Published anomaly

A quiet fishing spot stays full only while nobody knows about it. Print its location in a magazine and by next season the water is crowded with boats and the catch is thin. A published anomaly is a market pattern that a research paper has documented: a return that the standard models say should not be there, found in past data and written up for anyone to read.

The paper measured the past, often decades of it, and much of that past came before anyone knew about the pattern. Once it is published, professionals trade it, and their trading tends to shrink it. Studies that revisit old anomalies after publication usually find them weaker, and weakest in the largest, most watched companies. A number taken from a paper's sample years is a statement about those years, not a forecast.

That is why the logbook sounds published patterns in the years after the paper appeared, and in the universe a real account can trade. Post-earnings drift is in every textbook, and in the logbook's earnings entry it was close to zero among large companies today. The textbook is not wrong about the past; it is silent about the present. The question for any pitch built on a paper: when was it published, and what has the pattern done since?