Nick Clegg has made almost $19m (£15.3m) from the sale of shares in Meta since he joined the owner of Facebook, Instagram and WhatsApp six years ago.

The former British deputy prime minister announced on Thursday he was leaving his role as president of global affairs and communications.

Clegg, who was knighted in 2018 for political and public service, has sold $18.4m worth of shares in Meta since he joined the company.

His total pay at Meta has not been disclosed but he still holds almost 39,000 of the company’s shares, worth about $21m at their current price.

The former leader of the Liberal Democrats was heavily criticised for taking a role as Facebook’s vice‑president for global affairs and communications in 2018. At the time he was a leading supporter of the People’s Vote campaign and part of a high-powered pro-remain group of former politicians lobbying to stop Brexit.

Explaining the reason for his abrupt exit from the fight, Clegg said that, once he had signed up to join the Silicon Valley company and decided to relocate to the US, he might as well leave as soon as possible.

“I have mixed feelings about leaving the UK’s public debate about the future of our country’s relations with the rest of Europe,” he said, writing for the Guardian.

“The Brexit drama will soon move to – and possibly culminate in – the place where it arguably belonged all along, in parliament. I will no longer seek to play a public role in that debate. Once I had decided to accept a new role in Facebook, there was little merit in delaying my move any longer.”

Nonetheless, his decision to accept the high-profile role, at a time when the company was struggling to cope with mounting political pressure over issues including fake news, data protection and government regulation, has proved to be hugely lucrative.

Filings at the US Securities and Exchange Commission (SEC) showed that Clegg’s most recent sale of shares was in November at a market value of just over $4m, although the exact gross proceeds of the latest transaction have yet to be made public.

He was promoted to president of global affairs at Meta in 2022 – reporting directly to the founder and chief executive, Mark Zuckerberg. Clegg partly relocated to London that year, splitting time between the UK and California. He will be replaced by his deputy, Joel Kaplan.

Kaplan, who previously served as the deputy chief of staff for policy under the former president George W Bush, is known to be the most prominent conservative voice at the company. He rose to the top ranks at a time when Facebook faced claims of liberal bias.

Clegg said in a post on Facebook on Thursday: “It truly has been an adventure of a lifetime! I am proud of the work I have been able to do leading and supporting teams across the company to ensure innovation can go hand in hand with increased transparency and accountability, and with new forms of governance.”

Speculation is rife about what the 57-year-old may do next, and whether he may countenance a return to politics.

The Lib Dems won a record number of seats for the party at the general election last year.

Clegg managed to get the Lib Dems into power through a coalition with David Cameron’s Conservatives in 2010 but resigned as leader five years later after taking the blame for his party’s 2015 election defeat, which he described as “immeasurably more crushing and unkind” than he had feared.

He subsequently lost his seat in the 2017 general election and subsequently said that he “never had any desire to sit in an unreformed House of Lords”.

Meta has been approached for comment.