KEY POINTS
  • Massachusetts Secretary of the Commonwealth William Galvin told CNBC the GameStop trading frenzy represents a risk to the U.S. stock market.
  • "The marketplace should be a place where risk is taken, but not reckless risk," the securities regulator said.
  • Brokerages such as TD Ameritrade have placed restrictions on trading activity involving GameStop and AMC Entertainment.

The wild trading involving GameStop shares presents a broader threat to the U.S. equity market, the chief securities regulator in Massachusetts told CNBC on Wednesday.

"The marketplace should be a place where risk is taken, but not reckless risk and not a situation that undermines the system, and that's what we're looking at here," Massachusetts Secretary of the Commonwealth William Galvin said on "The Exchange."