Question: What are the most common ARM indexes?

Answer: The six-month and one-year T-Bill are generally seen as benchmark indexes. They tend to go up and down with some speed as they reflect movements in the financial marketplace.

The LIBOR (the London Interbank Offering Rate) is based in London and it has paralleled treasury securities. That said, if you want something that parallels treasury securities, why not use the 6-month T-bill index?

The 11th District Cost of Funds index is used nationwide even though it reflects lender borrowing costs in California, Arizona, and Nevada. It is an excellent index, slow to rise and slow to fall.