After dropping off the radar since its fall from grace during the financial crisis, the rate at which banks say they borrow from one another may be becoming relevant again.

The three-month London interbank offered rate, known as Libor, rose this week to a more than two-year high. That may be foreshadowing an interest-rate increase by the Federal Reserve by the end of year while other indicators such as futures provide more skeptical outlooks on the timing of tightening.

Minutes released Wednesday from the Federal Open Market Committee's April meeting show policy makers are weighing incoming economic reports as they debate raising borrowing costs for the first time since 2006. Libor is driven in part by the outlook for the Fed's policy rate as well as the level of credit risk in the banking sector, which is why it is at a premium to the funds rate.