Interesting study, but I think the experimental design was pretty weak. The Moon Affects The Stock Market is a trendy headline, but the results are basically me

Interesting study, but I think the experimental design was pretty weak. The Moon Affects The Stock Market is a trendy headline, but the results are basically meaningless without a plausible method of action. I'd like to see some data about why the moon affects the stocks. If it were me, I'd break the data in to smaller time series and try to control for the known effects of the moon. Does the full moon have the same effect on the stock market on overcast nights as it does on clear nights? Is the effect significant for countries and cities with lots of artificial lighting compared to those where the moon provides more artificial light? Personally, I'd be interested in how stocks traded at particular exchanges did. I live in Chicago right now, and the light pollution is so bad I barely notice the moon. I'm always amazed by how much a full moon illuminates the world when I am elsewhere. Does the full moon keep people up at night? Maybe people stay out later when the moon is full because the world is more brightly lit. Then they show up to the markets tired/hungover, affecting market performance. Chicago has a HUGE financial sector. If controlling for the city is too difficult, you may be able to look at commodities, like grain, since Chicago has a huge commodity exchange.