RENEE MONTAGNE, HOST:

Good morning. I'm Renée Montagne. Among the different theories as to why stock markets rise and fall, here's evidence that it's entirely unpredictable. Meet Orlando, the stock market cat.

Britain's Observer newspaper ran an investment challenge in 2012, pitting stock brokers against Orlando. The calculating kitty chose stocks by batting a toy mouse onto a grid of options - and his portfolio came out ahead. How's that for a Wall Street fat cat?

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