Here's something you could do instead; I am going to do the following starting in a few days when I get my Discover It Cashback card in the mail:
Sign up for a new card, e.g. Discover It Cashback, and you get 0% APR for 15 months on purchases. Instead of paying it off each month pay the minimum and put all that extra cash into federal money market. Run the card up to the limit and pay it off a couple weeks before the 0% APR promotion ends (in about 15 months).
With the Discover It Cashback, you also get 5% cash back on rotating categories, but the first year is double cash back so 10% cash back. You can buy Walmart/Sams club gift cards in any quarter usually with some hackin', and therefore get 10% cash back at walmart/sams year round (up to $1500 in purchases each quarter). You also get $100 sign up bonus with a friend's referral link. Also get 2% cash back on any other purchases for the first year (due to double cash back), 1% otherwise.