Arc is a company that offers diversification of startup deposits by providing up to 100% coverage across various FDIC, SIPC, and government-backed accounts. They enable companies to earn a maximum of 4.95% APY. The coverage includes $250K FDIC insurance on checking and savings accounts, $500K SIPC insurance on Money Market Funds with BNY Mellon Pershing, and government-backing on all funds stored in T-Bills.