Kaiko data show that Circle's USDC now represents 56% of stablecoin trading against the euro, compared with 10% in January 2024. The shift gained speed after major exchanges limited USDT trading for European Economic Area customers under the EU's Markets in Crypto-Assets Regulation (MiCA). USDC's euro-denominated order books are now about 40% deeper than USDT's. However, Tether's stablecoin remains larger worldwide, with circulating supply approximately 2.5 times USDC's. Kaiko said US regulation could produce a similar trading shift on American exchanges.