Circle Internet Group, Inc. announced the launch of the public testnet for Arc, a new open Layer-1 blockchain network. [1, 3, 4] Described as a new 'Economic Operating System for the internet,' Arc is designed to support enterprise and financial applications, enabling more economic activity to be brought onchain. [1, 2, 5] The launch includes collaboration with over one hundred companies, with prominent names like BlackRock, Visa, Apollo, BNY, and State Street participating in the testnet. [1, 2, 6] Arc's features include predictable dollar-based fees, sub-second transaction finality, and direct integration with Circle's platform, targeting use cases in lending, capital markets, and global payments. [1, 3] Following the announcement, the market reaction appeared positive, with one report noting that Circle's stock (CRCL) surged 8.88%, reflecting investor optimism about the new blockchain's potential. [7] The platform is seen as a move toward creating a neutral and open infrastructure for a global, internet-native economic system. [3, 7]