Nothing guarantees it, but what makes you think that a tool that is hooked up real-time to what people everywhere are thinking and querying wouldn't be a good p

Nothing guarantees it, but what makes you think that a tool that is hooked up real-time to what people everywhere are thinking and querying wouldn't be a good predictor for the stock market? The precise terms to use perform randomly as can be seen by the spread, so the fact that 'debt' came out on top is less interesting than the fact that the spread itself is significantly higher than what would be expected if the terms were distributed randomly with a mean impact of zero. Or as they put it in the paper, "The distribution of final portfolio values resulting from the random investment strategies is close to log-normal" ... "We find that returns from the Google Trends strategies we tested are significantly higher overall than returns from the random strategies (<R>US = 0.60; t = 8.65, df = 97, p < 0.001, one sample t-test)." What the paper is saying, is as a whole their basket of terms performed better than random strategies. You are free of course to try to reproduce this study to see if such a strategy can be used going forward. It would be interesting to investigate the effect of introducing a Bayesian aspect, such as investing more weight (money) into words that have been performing better, much like multi-armed bandit A/B testing. Edit: The selection of the basket of terms is of course important, whether it comes from knowing the recent history vs part of the algorithm is important as mentioned above about overfitting.