[ktaylora]

Fidelity and other major online brokerages do this with their money market accounts. It doesn't chase an optimal yield like what you are proposing, but that would be interesting. Instead, they use a large basket of money market and savings accounts at US banks and interest payments on your savings are drawn from a random bank in the basket each month. Because the federal reserve sets interest rates, it's difficult to chase yield in bank savings accounts. You'll always do better with bonds and stock dividends.