Libor, Long the Most Important Number in Finance, Dies at 52

Bankers used it until the end. Regulators say good riddance after its infamous fall.

The London interbank offered rate, a number that spent decades as a central force of international finance and was used in setting interest rates on everything from mortgages to student loans, has died after a long battle with regulators. It was 52.

Known as Libor, the interest-rate benchmark once underpinned more than $300 trillion in financial contracts but was undone after a yearslong market-rigging scandal came to light in 2008. It turned out that bankers had been coordinating with one another to manipulate the rate, pronounced “LIE-bore,” by skewing the number higher or lower for their banks’ gain.

Libor could no longer be used to calculate new deals as of Dec. 31 — more than six years after a former UBS trader was jailed for his efforts to manipulate it and others were fired, charged or acquitted. Global banks including Barclays, UBS and Royal Bank of Scotland ultimately paid more than $9 billion in fines for fixing the rate for their own profit.

Randal Quarles, then the Federal Reserve’s vice chair for supervision, offered a scathing early eulogy in October, saying Libor “was not what it purported to be.”

“It claimed to be a measure of the cost of bank funding in the London money markets, but over time it became more of an arbitrary and sometimes self-interested announcement of what banks simply wished to charge,” Mr. Quarles said.

While regulators and central bankers were relieved by its departure, Libor will be mourned by many bankers who used it to determine the interest rates for all kinds of financial products, from various types of mortgages to bonds.

“There are not many corners of the financial market that Libor hasn’t touched,” said Sonali Theisen, head of fixed-income electronic trading and market structure at Bank of America. Even so, she said, getting rid of it was “a necessary surgical extraction of a vital organ.”

Libor was born in 1969 to Minos Zombanakis, a Greek banker. The shah of Iran, Mohammed Reza Pahlavi, wanted an $80 million loan, and Mr. Zombanakis was willing to provide it. But the question of the interest rate to charge a sovereign ruler was a tricky one. So he looked to the rate that other well-heeled borrowers — London’s banks — would pay to borrow from one another.

In its early years, Libor was a growing but still adolescent rate, employed for a steadily increasing number of contracts. In 1986, at age 17, it hit the big time: Libor was taken in by the British Bankers Association, a trade group described later by The New York Times as a “club of gentlemen bankers.”

They effectively made it the basis for virtually all the business they conducted. Libor was the interest rate that banks themselves had to pay, so it offered a convenient base line for the rates they charged customers who wanted to borrow cash to buy a home or issue a security to finance a business expansion.

Libor became a number punched into almost any calculation involving financial products, from the humble to the exotic. The British banks used it to set rates for loans across the industry, whether denominated in dollars, British pounds, euros or Japanese yen. Never before had there been such a benchmark, and Libor’s daily movements were the very heartbeat of international finance.

But as Libor approached middle age, troubling health problems began to emerge.

By 2008, regulators in the United States and Britain began receiving information that banks’ rate reports were amiss. Because Libor relied on self-reported estimates, it was possible for a bank to submit a rate that was artificially high or low, thus making certain financial holdings more profitable.

Soon, news media reports cast doubt on Libor’s integrity, and investigators ultimately uncovered blatant misconduct in the rate-setting process. In one email released by regulators in 2012 as part of an investigation into Barclays, a trader thanked a banker at another firm for setting a lower rate by saying: “Dude, I owe you big time! Come over one day after work and I’m opening a bottle of Bollinger” — a reference to the Champagne producer.

The scandal grabbed international headlines, from the Financial Times to The Wall Street Journal to The New York Times. Before long, Libor was the butt of jokes on “The Daily Show.”