Four former Barclays bankers were sentenced to between 33 months and six-and-a-half years in jail by a London judge on Thursday for conspiring to rig global benchmark interest rates.

Calcutta-born Jay Merchant, 45, the most senior of the men to face a jury in the case, was sentenced to six-and-a-half years in the latest London Libor trial. The New York-based former derivatives trader was convicted unanimously.

Merchant's junior, 38-year-old American Alex Pabon, was sentenced to two years and nine months and junior British Libor submitter Jonathan Mathew, 35, was handed a four-year sentence. Both men were convicted by majority verdict.

Mathew's former boss, 61-year-old former Barclays veteran Peter Johnson was also sentenced to four years. The former senior dollar Libor submitter and head dollar cash trader pleaded guilty in October 2014 and did not stand trial.

Judge Anthony Leonard said the men had abused their position of trust, undermined the integrity of the banking industry and offended over a significant period. They will serve half their sentence in prison before being released on licence.

They were promptly led out of the glass-enclosed dock by court officials.

The sentences come four years after Barclays became the first of 11 powerful banks and brokerages to be slapped with a hefty fine for their role in the rate fixing scandal, sparking a political backlash that forced out former CEO Bob Diamond, an overhaul of Libor rules and the criminal inquiry.

Misconduct

The men had faced sentences of up to 10 years after they were each charged with one count of conspiracy to defraud by plotting to rig Libor (London interbank offered rate), a benchmark for rates on around $450 trillion of financial contracts and loans, between June 2005 and September 2007.

But the sentences fall far short of the original 14-year jail term handed last August to Tom Hayes, a mildly autistic former UBS and Citigroup trader, in the world's first Libor-rigging trial.

Judge Leonard accepted that the scale of Hayes’s misconduct, cast as a ringleader in a global conspiracy with staff from 10 other banks and brokerages to rig yen-denominated Libor over four years, was significantly different to the Barclays case.

Hayes’ sentence was cut to 11 years on appeal and he plans a further appeal.

Two British former Rabobank bankers, Anthony Allen and Anthony Conti, were subsequently sentenced to two years and one year and a day in prison respectively in the first U.S. Libor trial.

But judge Leonard declined to take the comparative lightness of those U.S. jail terms into consideration.

"The sentences for each of those convicted of Libor rigging varies significantly, which indicates that the judge has taken a highly fact-sensitive approach in each case," said David Corker, a partner at law firm Corker Binning.

A lawyer for Pabon declined to comment. Lawyers for the other men did not immediately respond to requests for comment.

Cheating

Prosecutors said New York-based Merchant and Pabon were driven by greed to scheme with London-based Libor submitters, responsible for sending the bank’s daily cost of borrowing estimates to a Libor administrator, to skew rates to make more money for themselves and Barclays and cheat others.

In an 11-week trial, the Barclays traders denied dishonesty, argued their bosses sanctioned attempts to influence rates, that they did so in full view of compliance staff and that such practices were widespread at the time.

Johnson had pleaded guilty at the earliest opportunity. He expressed contrition and said he was motivated only by a desire to be a team player and had not adjusted rates to suit his own trading book. He also denied allegations that he bullied Mathew.

James Hines, leading SFO counsel, has told the court traders stopped trying to influence Libor rates when the credit crisis struck in the fourth quarter of 2007 only because another form of Libor manipulation began.

He said there was “little doubt” that Johnson had been instructed to reduce Libor submissions by senior Barclays management keen to paint a rosier picture of its financial health in a practice that has become known as “low-balling”.

Barclays in 2012 admitted and accepted responsibility for low-balling during the credit crisis and for allowing derivatives traders to manipulate Libor rates. It paid a then-record $450 million penalty to U.S. and European authorities.

(Reporting By Kirstin Ridley; editing by Jon Boyle and Keith Weir)