WASHINGTON, May 5 (Reuters) - The U.S. securities regulator is considering measures to boost transparency around “short-selling” and equity derivative bets and to rein-in retail “gamification” following January’s GameStop saga and the meltdown of Archegos Capital, its new chair will tell lawmakers. Gary Gensler will testify before the House Financial Services Committee on Thursday, according to testimony published on the committee’s website, in his first appearance before Congress since he was sworn-in as Securities and Exchange Commission chair last month. (Reporting by Katanga Johnson Editing by Chris Reese) Our Standards: The Thomson Reuters Trust Principles.