Interview question: Evaluate the predictive power of a signal to predict stock

This seems to be a popular interview question now to predict stock market. Are they stealing your idea to make money to make it their own? Be careful out there as employers are renowned for trying to own your ideas!

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https://quant.stackexchange.com/questions/71086/evaluate-the-predictive-power-of-a-signal-to-predict-stock-price-interview-que