The 5 biggest M&A deals of the year (so far)

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2015 has been a boom year for mergers and acquisitions (M&A), as companies around the world seek to expand and diversify at a time when the global economy looks reasonably healthy.

Globally, M&A activity has reached a value of $3.24 trillion year-to-date, just shy of the record $3.43 trillion reached by this point in 2007, according to data provided for CNBC by Dealogic.

This week alone, Japan's MS&AD Insurance Group Holdings bought U.K. rival Amlin for $5.34 billion and European officials approved General Electric 's $14 billion acquisition of Alstom's energy business.

Almost 26,000 M&A deals have been announced this year and biggest deals have been in healthcare, tech and energy. Here are the five biggest deals of the year so far, using data from Dealogic.

Royal Dutch Shell and BG Group: $81.5B

Shell announced it would buy British energy supplier BG in April in order to grow its liquefied gas and deep water exploration capabilities. Dealogic valued the deal at $81.5 billion, making it this year's biggest so far.

Charter Communications Time Warner Cable: $79.6B

In late May, Charter Communications , a U.S. telecoms and broadband provider, announced it would buy Time Warner Cable in a deal valued at $79.6 billion.

The merger expanded Charter's footprint in the U.S. by 84,000 square miles, vastly increasing its customer base. The deal will also include the purchase of Bright House Networks, a smaller telecoms and broadband provider.

Energy Transfer Equity and Williams: $70.6B

A $48 billion takeover bid by Energy Transfer Equity was rejected by energy provider Williams in June, but the U.S. pipeline company said in July that it would continue to pursue a deal, which Dealogic values at $70.6 billion.

A merger would greatly expand Energy Transfer Equity's natural gas pipeline network, as well as give it access to the Gulf of Mexico.

Heinz and Kraft Foods: $62.6B

The biggest completed deal of 2015 so far, this merger between the two food and beverage giants was valued at $62.6 billion. The newly created Kraft Heinz Company is the third-largest food company in the U.S. and fifth-largest in the world, measured by annual sales.

Anthem Inc and Cigna Corporation: $55.2B

The U.S. health insurance providers announced a merger late in July. The deal, valued at $55.2 billion, would create the largest health insurer in the country, with around 53 million customers.

However, the deal faces a lot of scrutiny from anti-trust regulators. A report published this week by the American Medical Association claims it would reduce industry competition across 14 states.

Follow Luke of Twitter: @LukeWGraham

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