Libor Doesn’t Have to Mean Libor

My basic theory of Libor, the London interbank offered rate, is that it is a function call. You want to have a contract that specifies a floating interest rate, one that changes (say) every quarter based on prevailing interest rates. One way to do that is specify in the contract that, each quarter, you will observe some market data and call some banks for quotes and do some calculations and produce a number, the number being the interest rate. The contract could spell out the entire methodology to take some facts about the world and convert them into an interest rate.

But the way Libor works in contracts is mostly not like that. The way Libor works in contracts is mostly by saying “the interest rate will be whatever Libor says it is.” (Plus a fixed spread.) Exactly how that is expressed varies, but it is generally expressed by reference to some source, either the official administrator of Libor (formerly the British Bankers’ Association, now Intercontinental Exchange Benchmark Administration) or a Bloomberg or Reuters page that displays the official Libor.2