Spies are often in it for the money. Some recent examples:
None of this is new. Spying to help rich cronies has been going on forever. Wikipedia has a good summary of an historical program called ECHELON. It's full of details about when they were caught in the 1990s. You may want to search the page for the words "economic" and "industrial". As always, search engines have more.
And there's much more to come. The GCHQ/NSA "quantum insert" attacks (see 1, 2, 3) might have been tailored for HFT (High Frequency Trading) systems. All they need is to be a little bit faster than their victims.