occasionally, banks may not have enough money in their federal reserve accounts to fulfill their withdrawals. for example, assume bank a has $10 million as their assets and the federal reserve requires 10% of their assets as their reserves, which is $1 million. if one day, bank a needs to transfer out $1.5 million during the day, bank a is running a daylight overdraft during that day. by the end of that particular day, bank a has an obligation to pay back the federal reserve.