Investors who can afford to hire satellites to scan parking lots are finding a significant edge in the stock market.

Satellite speculators have reportedly used techniques like car-counting, tracking oil inventories or watching corn fields to make profitable forecasts of equity and commodity markets. Now, research from finance professors at UC Berkeley and the University of Kentucky provides the first independent evidence that these trading strategies work—and that they’re likely being used to the detriment of small-time investors.

Read more at QZ.