random walk theory

British  

noun

1. stock exchange the theory that the future movement of share prices does not reflect past movements and therefore will not follow a discernible pattern

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Example Sentences

We meet the “mosquito man,” Sir Ronald Ross, whose study “The Logical Basis of the Sanitary Policy of Mosquito Reduction” became the foundation of the so-called random walk theory.

From New York Times

Then again, there’s always the so-called “random walk” theory to investing. 

From Forbes