UK insurance broker Jardine Lloyd Thompson (JLT) is being snapped up by Marsh & McLennan in a £4.3 billion deal, putting thousands of jobs at risk.

The recommended all-cash deal will see JLT shareholders offered £19.15 per share, representing a 33.7% premium on its closing price on September 17.

The deal values the entirety of JLT at around £4.9 billion.

Marsh & McLennan Companies MMC plans to maintain its headquarters in New York, and while there may be plans to combine certain offices and functions, it “expects to have an even larger presence in London and the UK more broadly”.

But overlap between the two firms could result in up to 3,750 job losses across the combined business.

An initial review identified some likely duplication between the two firms “particularly in functional support areas, and plans to take a “best of both” approach to the integration.

“MMC’s preliminary evaluation suggests that MMC is expected to achieve synergies of approximately 250 million US dollars (£190 million) within three years of completion of the acquisition, a substantial portion of which could come from headcount reductions in addition to savings in real estate, IT, outside services and other initiatives,” the market announcement explained.

“Based on this preliminary evaluation, MMC expects a potential headcount reduction of between 2% and 5% of the total combined group workforce across all geographies, including in the UK, Continental Europe, Asia, North America, the Middle East, Latin America and the Pacific, and from a broad range of job categories.”

It said job cuts could impact roles across functional support areas such as finance, human resources, IT, operations, legal and administrative support staff.

JLT operates in over 40 territories with over 10,000 staff, while MMC’s 65,000 employees serve clients in over 130 countries.

Once the takeover is completed, JLT chief executive Dominic Burke will join MMC as vice chairman and serve as a member of its executive committee.

The deal – which is still subject to competition clearances and regulatory approvals – is expected to close in spring 2019.

Executives from both firms cheered the deal, saying it was a “compelling” combination.

Dan Glaser, president and chief executive of MMC, said: “The combination of MMC and JLT creates a compelling value proposition for our clients, our colleagues and our shareholders.

“JLT is a complementary strategic fit with MMC. Bringing together our two enterprises will create a platform to deliver exceptional service to clients across geographies and specialities.

“At a personal level, I have come to know, and respect, Dominic Burke and his management team from my time both at MMC and as an underwriter.

“I am confident that the addition of JLT’s talented colleagues will make us an even stronger and more dynamic company.”

MMC – which itself is primarily an insurance broker and consultancy – said the deal will boost plans to be a global leader in “offering clients advice and solutions in the areas of risk, strategy and people.”

It expects the move to strengthen its speciality risk broking business and expand its global reinsurance operations.

“This transaction also provides an opportunity for MMC to enhance several areas of JLT’s business, including accelerating growth in global employee benefits and their US expansion,” the market announcement said.

Overall, it is estimated that MMC’s revenues will rise to around 17 billion US dollars (£12.9 billion) as a result of the acquisition.