‘China Hustle’ a mildly engrossing yet wonky investment documentary

The phenomenon of “shorting” — a financial maneuver in which an investor only makes money if a stock fails — is the subject of “The China Hustle,” a documentary by Jed Rothstein (director of the 2010 Oscar-nominated short “Killing in the Name”). Its setting is China, where many companies have lured American investors with fraudulent promises of financial prosperity.

That’s according to Dan David, the film’s main subject, tour guide and one of a handful of short-sellers featured in the film who are trying to make money by, in essence, betting against the success of those firms. Their participation in “China Hustle,” which is an exposé, is, of course, self-serving. The more attention they can bring to the sham — some of the Chinese companies featured appear to do little or no actual business — the greater the odds are that the Dan Davids of the world will eventually cash in when the companies they have shorted collapse.

It’s a mildly engrossing if wonky exercise in what could be called a kind of selfish activism. (Anyone who saw the 2016 documentary “Betting on Zero” or the fact-based 2015 comedy-drama “The Big Short” will already be familiar with the practice of shorting, which aims to profit from putting corrupt — or simply incompetent — firms out of businesses.)

If the film accomplishes its goal, it’s a win-win-lose proposition for everyone concerned. Filmgoers are warned away from making bad investments; David and his fellow short-sellers make a killing; and the crooked Chinese companies go down the toilet.