Max helps you spread your cash out across multiple banks to keep you below the FDIC insurance limit at each bank.
By default, Max proposes that at the completion of each optimization, you desire to have no more than $248,500 in each online savings account (this leaves a $1500 cushion below the current FDIC insurance limit of $250,000, so that interest that accrues through the date of your next optimization can also be insured). If you indicate that you have joint accounts, by default, Max will propose keeping your balances below $500,000 per account.
Note: FDIC insurance is provided by your banks, not by Max. If you choose to increase your per-account limits above the FDIC insurance limit, your funds may be at risk in the event of a bank failure.