/biz/ - Business & Finance

I had an idea for a new layer to credit cards. I doubt I will ever be able to pull it off but the idea goes like this.
People open a credit card with you, say limit of $2000. At the same time they open a $2000 "zero" interest loan (they don't actually receive any money). And every month they "earn" interest on the unused portion of the "loan" compared to their credit card balance. With that "loan", "backed" by the user, we (the company) simply put it into investment grade bonds or a mutual fund.
For example:
Jenny opens a card for $2000. The company "loans" them $2000 which they keep and invest in bonds/mutual fund. Jenny uses her card like a normal credit card, and at the end of the month, he balance is $250. We would give her "rewards" for the $1750 she hadn't spent (minus any fees, like a normal credit card). So if that month the fund made 1%, jenny would earn up to 0.9% (but probably much less, like .5% to account for down months) on $1750. She earned $15 for doing nothing! And the company pockets the difference.

What do you think of this scheme?