Janet Yellen speaks in 2019.

Wall Street is concerned about the Yellen regulator super summit, and with good reason, market watchers say.

"The Street should be worried," said Jamie Selway, former head of electronic brokerage at ITG and now an investment advisor. "There's clearly questions about gamification, and whether a lot of these approaches are suitable and inducing unnecessary trading activity. Regulators are starting to look at what kind of behaviors can be induced through those apps."