The USD ARM is a vault that earns yield by buying discounted stablecoin from the market using USDC, and then redeeming them to earn a yield. Vault liquidity not being used to arbitrage the withdrawal queue is routed to lending markets to earn additional yield. This token was built and designed by the team behind Origin Protocol. Other ARMs that have been launched include: stETH ARM, eETH ARM, and the sUSDe ARM.