US prosecutors have charged Danielle Sindzingre, 54, and Muriel Bescond, 49, with one count of conspiring to transmit false reports concerning market information that tends to affect a commodity and four counts of transmitting such false reports.
At the time Ms Sindzingre was the global head of treasury while Ms Bescond was the head of treasury for Paris at the financial institution.
It is alleged that between May 2010 and October 2011 the pair told subordinates at Société Générale’s Paris treasury desk to submit inaccurately low Libor contributions to allow the bank to borrow money at more favourable rates.
In total, prosecutors estimate that the pair’s misconduct caused more than $170m (£132.5m) in damage to global financial markets.
Kenneth Blanco, acting assistant attorney general at the US Justice Department’s criminal division, said: “The allegations in today’s indictment suggest complete and total disregard for the integrity of the financial markets and for innocent consumers and everyday people whose personal finances hinge on the interest rates they pay on various loans.
“Cases like this demonstrate the crucial role of the department in protecting people and their hard earned money, securing our financial markets for economic growth and prosperity, and for fighting white collar crime to protect our nation from bad actors, wherever they may reside.”
Chief executive of the Financial Conduct Authority Andrew Bailey confirmed last month that Libor, which is used to price $350tn-worth of mortgages, loans and other transactions, would be phased out by 2021 and replaced by a new benchmark following a transition period.
It follows a string of high-profile scandals in which the rate was manipulated by traders to boost their institutions’ profits.