FNMA LIBOR is one of a number of widely-used 'flavors' of LIBOR. The index history shown here was commonly used as an index on residential mortgages. The daily LIBOR index, published by The Wall Street Journal, is not directly related to the monthly point-in-time Fannie Mae version shown below.
FNMA LIBOR was discontinued with the June 2007 values. See here for the explanation. For continuity purposes, HSH produces a replacement index.
Fannie Mae LIBOR rates were formerly determined from information that was available as of 11:00 a.m. (London Time) on the second to last business day of each month. Fannie Mae made these rates available by the last business day of each month.
Over time, certain WSJ and other published LIBORs have become commonly used in ARM contracts. To be certain, check your loan contract for the name, frequency and source of the index which governs your ARM.
LIBOR is an abbreviation for "London Interbank Offered Rate," and is the interest rate offered by a specific group of London banks for U.S. dollar deposits of a stated maturity. LIBOR is used as a base index for setting rates of some adjustable rate financial instruments, including Adjustable Rate Mortgages (ARMs).
Note that while this may appear to be related to the daily LIBOR released by the BBA, this is not the same index.