Fidelity offers miles for opening and funding brokerage accounts, up to 25,000 United, Delta, or American miles for $50,000 deposited.

That’s a pretty good tax free return in a market where making a decent taxable return is iffy at best. (And via Free Frequent Flyer Miles, Delta is offering a 25% bonus on miles earned through their financial partners until July 15.)

But the real trick is this: a Flyertalk thread suggests that you don’t really need to deposit $50,000 to earn the 25,000 miles … you can deposit, withdraw, and re-deposit the same money to reach $50,000 in total deposits (eg the same $10,000 deposited 5 times).