Shares of Circle Internet Corp. (CRCL) tumbled 5.08% during intraday trading on Thursday, as investors reacted to growing concerns over the proposed CLARITY Act and its potential to disrupt the company's stablecoin business.

According to a recent research report from Mizuho Bank, the legislation could fundamentally reshape the competitive landscape for stablecoins by removing regulatory uncertainty, which may paradoxically invite intensified competition. The report highlights Open USD as a core threat, backed by a consortium of over 140 major companies including Visa, Mastercard, Stripe, BlackRock, and Coinbase. Open USD's revenue-sharing model distributes the majority of reserve earnings to its partners, whereas Circle retains only about 38% of USDC's reserve earnings, making Open USD significantly more attractive to large distribution partners.

A critical variable identified by analysts is the dual role of Coinbase, which serves as both the largest distributor of USDC and a backer of Open USD. Mizuho predicts Coinbase could begin renegotiating its revenue-sharing agreement with Circle as early as next month, leveraging its pivotal position to secure more favorable terms. Such a move could erode Circle's competitive moat and directly alter the balance of power in the stablecoin market, presenting a serious challenge to the company's established first-mover advantage and profitability.