An alleged conspiracy among over a dozen banks to rig a major interest rate at the center of the international financial system has resulted in a single conviction.

Tom Hayes, 35 years old, will go to jail for 14 years after a London jury said he was the "ringmaster" who manipulated the London Interbank Lending Rate, or Libor, between 2006 and 2010. Hayes, a trader, worked at Citibank and UBS specializing in securities that were pegged to the Libor rate connected to the Japanese yen.

The judge in the case admonished Hayes for a "lack of integrity."

Hayes was nicknamed "Rain Man", and slept under superhero duvet cover he had owned since he was eight, Reuters reported.

Hayes' conviction is a surprise in part for its severity and length. If he serves his full sentence, he will be nearly 50 years old before he emerges from jail. No one else, including senior banking executives, has been convicted.

Hayes' trial also shows the because he didn't even work at one of the banks long investigated at the center of the scandal: Barclays, which paid $450 million to settle charges around its involvement. Barclays' then-chief executive, Bob Diamond, testified in front of UK parliamentary committee that the idea of 14 of his traders allegedly rigging a major interest rate "made him physically sick." In 48 hours, the bank lost several of its major executives.

The UK Financial Services Authority found email and chat from traders at Barclays pinging each other with requests to rig the interest rate followed by enthusiastic language like "anything for you!!!!!!" and "thanks a million dude!"

Prosecutors argued that Hayes led a ring of at least 10 traders at various banks.

Libor is a key rate that banks use to borrow from each other. It also affects student loans, mortgages, and car loans, although through a complicated mechanism that makes it hard to trace the rate's movements.

Hayes is the first to be convicted by a U.K. jury of Libor rigging.

Prosecutor Mukul Chawla said Hayes "behaved in a thoroughly dishonest and manipulative manner" and called him the ringmaster at the center who told others what to do and rewarded them for their "dishonest assistance."

"The motive was a simple one: it was greed," he said.

Hayes claimed his bosses knew what he was doing "with complete transparency."

"Everything I did my managers knew about," Hayes said. "Sometimes going up all the way to the CEO."

—The Associated Press contributed reporting