As of 2017, this offer has expired. 

File this one under “You need money to make money” – or, in this case, to make miles.

But if you have between $25,000 and $100,000 in another brokerage account, you can get up to 50,000 bonus miles on American Airlines, United Airlines, or Delta by moving money or securites to Fidelity. If you have multiples of this, you can do the same thing every year.  If you have this amount in a Fidelity account now, and nothing elsewhere, you can transfer it out, wait a while, and then do the deal and move it back in.

How it works:

Fidelity offers this program for both new and existing customers and in personal non-returement accounts only. You simply need to move money or securities in the following amounts to earn the associated bonus:

Deposit amount $25,000+ $50,000+ $100,000+
Miles earned 15,000 25,000 50,000
Since you can only do it once per year, it makes sense to max this out to the best of your means.
You will need to leave the money or securities in the account for 9 months. At your one year anniversary of doing the promotion, you can do it again. Now if you try to basically withdraw the money at 9 months and put the same money back in at 12 months, my hunch is that it will work but they will probably not let you do it the third time around.  If you withdraw before 9 months, you will be banned from ever registering again.
But if you maintain a brokerage account elsewhere there is nothing stopping you from slowly moving securities over to Fidelity. Let’s say you had $500,000 in a TD Ameritrade account. Over 5 years you could liquidate that over to Fidelity and earn 250,000 miles in the process for doing basically nothing. If you move securities there is no associated opportunity cost. You could move cash into the account and get the bonus, but I wouldn’t advise that as you will just be losing the interest you could earn elsewhere.

Can I do this more than once a year by opening multiple accounts?

If you have someone else you can open a joint account with, yes. But you cannot otherwise open multiple accounts yourself as it goes by your social security number.

How to register for the promotion:

You need to use the associated link to register for the miles you want.

For United Airlines miles, use this link

For Delta miles, use this link

For American Airlines miles, use this link