Steven Mnuchin’s private equity group made its first buyout since stepping down as U.S. Treasury Secretary in the Trump administration, taking a majority stake in mobile cybersecurity firm Zimperium for $525 million. dollars.

Liberty Strategic Capital, Mnuchin’s company, has focused on cybersecurity with four minority investments since its launch last year. Mnuchin has raised $2.5 billion from a group of backers including Japan’s SoftBank, Saudi Arabia’s Public Investment Fund and Abu Dhabi’s Mubadala.

Zimperium, founded by two Israeli security experts, provides companies with technology to prevent criminals from hacking into their employees’ mobile devices to obtain sensitive information.

The Dallas-based company says it is capable of thwarting mobile attacks such as the one carried out by NSO Group’s Pegasus, the Israeli maker of military-grade spyware that has created software to track the phones of journalists and activists in the human rights around the world.

“It’s clear that mobile is the new frontline for cybersecurity,” Mnuchin said. “We believe that Zimperium has positioned itself as the leader in securing mobile devices and applications.”

Prior to joining Donald Trump’s administration, Mnuchin worked for several years on Wall Street, rising to the top ranks of investment bank Goldman Sachs.

He left Goldman in 2002 and later started hedge fund Dune Capital Management and a movie studio called Dune Entertainment. After the 2008 financial crisis, he went on to turn around bankrupt California lender IndyMac, which was later acquired by CIT Group for $3.4 billion.

Mnuchin was not the first Treasury secretary to have previously worked at an investment bank. Many then left government to join the lucrative world of private equity buyouts.

John Snow, who served under President George W Bush, has joined Cerberus Capital Management, while Tim Geithner, Barack Obama’s first Treasury Secretary, is chairman of Warburg Pincus, which will sell its stake in Zimperium.

Jack Lew, Obama’s second treasury secretary, is managing partner of the private equity group Lindsay Goldberg, and Hank Paulson, who also served under Bush, is executive chairman of a climate investment fund at TPG.