A market theory that states stock prices and aspirin production are inversely related. The Aspirin count theory is a lagging indicator and actually hasn't been formally tested, so it is more a humorous hypothesis than a theory.

Investopedia Says:
As stock prices fall, more and more people need pain relievers to get through the day. For example the Aspirin count theory would predict that as aspirin sales increase, the stock market's value decreases and vice versa.

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