US watchdog the Commodity Futures Trading Commission (CFTC) has awarded a record almost $200m to a former Deutsche Bank employee who raised the alarm about Libor-rigging, in the biggest-ever US whistleblower payout.

The regulator said the payment had been made for “specific, credible and timely original information” that “significantly contributed” to an already “open investigation” by authorities in the US and UK.

Their decision to blow the whistle led to a “successful enforcement action, as well as to the success of two related actions, by a US federal regulator and a foreign regulator,” the CFTC said in a statement.

While the watchdog did not provide the name of the whistleblower or their employer, sources familiar with the matter have identified them as a former Deutsche Bank employee, and the payout is understood to be related to the £2.5bn settlement the bank paid to US authorities in 2015.

It followed a regulatory investigation into the manipulation by a network of banks and traders who teamed together to rig global benchmarks – most famously the London Interbank Offered Rate (LIBOR).

Barclays, Deutsche Bank and Société Générale were among the banks fined by the CFTC and other watchdogs over the scandal.

“The whistleblower award amount may seem shocking but it’s because the ability to manipulate and make huge profits is shocking,” said David Kovel, the whistleblower attorney from Kirby McInerney. “It follows from the misconduct.”

Until now, the biggest-ever whistleblower award handed out by the CFTC’s bigger brother, the Securities and Exchange Commission, stood at $114m.