[jojobas]

Except

1) Chase doesn't have to show you $0, you'll still see $100.

2) When you decide to spend the money, chances are the seller is also with Chase, then all Chase has to do is show you $0 and the seller +$100

3) If the seller happens to be with another bank, Chase will just go in credit with that other bank for $100. The total of such interbank accounts is around 0 as money flows both ways, and, with a decent margin, within the bank reserve amount.

Fractional-reserve banking works so well with so little "actual" reserve money that some consider it counterfeiting.

[colinmhayes]

Eventually the other bank will ask for settlement. Maybe it’s because you owe them a billion dollars and they have a liquidity crisis. Whatever the reason is, you can’t just go on forever “oweing” then money.