LONDON (AFP) - The volume of mergers and acquisitions worldwide set a new record in 2015 at more than US$5 trillion (S$7 trillion), with tie-ups in the health-care sector leading the way, consultants Dealogic said on Tuesday.

The US$5.03 trillion annual total represents a massive rise of 37 per cent from 2014, Dealogic said, and the three months to December scored the highest figure for any single quarter on record.

Pfizer's proposed US$160 billion merger with Allergan to create the world's biggest pharmaceutical group, announced last month, is the second-biggest tie-up ever, and the largest ever in health care.

The two companies estimated their merger will deliver more than US$2 billion in operational synergies over the first three years after closing.

Thanks to that operation, the health-care sector chalked up the largest share of 2015 merger and acquisitions volume with US$724 billion, followed by technology, US$713 billion, and real estate, US$458 billion, Dealogic said.

The year's second-largest deal was the US$117.4 billion bid by top global brewer Anheuser-Busch InBev for its closest rival SABMiller, also announced in November.

The blockbuster transaction will bring together InBev's top lagers like Beck's, Budweiser and Stella Artois with SABMiller brands Foster's, Grolsch and Peroni.

Belgian-Brazilian behemoth InBev is eager to tap into booming developing markets in Africa and China, where SABMiller's joint venture produces Snow - the world's best-selling beer by volume.

Dealogic said the year's top two operations are among only eight mergers in history topping US$100 billion.

The third-largest deal was a US$81.5 billion tie-up between Royal Dutch Shell and BG Group, flagged in April. The deal is aimed at helping Shell boost its weakening output thanks to BG's strong position in liquefied natural gas (LNG), a cleaner alternative to coal and nuclear energy.

This year was marked by particularly large mergers. There were 69 deals in 2015 exceeding US$10 billion, more than double last year's level and also a new record.

Mega deals of US$50 billion or more accounted for nearly one in six of all the year's deals - a share for heavyweights never seen before.

This year's total was more than double that seen in 2009, the year following the outbreak of the global financial crisis.

Goldman Sachs was the world's leading advisor for mergers and acquisitions this year, followed by Morgan Stanley and JP Morgan, Dealogic said.