Exchanges are expected to introduce new trading curbs known as circuit breakers for large U.S. stocks over a six-month pilot program, as regulators move to avoid a repeat of the severe market plunge on May 6, two people familiar with the talks said on Tuesday.

The circuit breakers need to be in place and operational by June 14, one of the sources said. Both sources requested anonymity because the talks are private.

Multiple sources previously told Reuters the breakers would halt all trading when individual stocks drop or rise by 10 percent in five minutes.

Securities and Exchange Commission Chairman Mary Schapiro said earlier the regulator will unveil the new rules Tuesday.

(Reporting by Jonathan Spicer and Rachelle Younglai; Editing by Lisa Von Ahn)