These 10 M&A deals defined the 2010s. Here's how they upended industries, drew regulatory ire, and transformed dealmaking.

Getty; Samantha Lee/Business Insider

Facebook's $1 billion Instagram acquisition turned out to be one of the most lucrative and consequential tech acquisitions of the decade.

• The decade started off cold, but the 2010s produced some of the frothiest years for mergers and acquisitions in history.
• Business Insider spoke with M&A bankers, lawyers, and academics to determine 10 of the most significant deals of the decade.
• While some of the largest deals of the 2010s appear on this list, this is not a list of the largest deals of the 2010s - we considered and included deals of all sizes and from a variety of industries.
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With the economy in the dumps and gun-shy corporate boards hoarding cash following the financial crisis, mergers and acquisitions were ice-cold at the start of this decade.

But in the ensuing years, a 10-year bull market unfolded, economic fortunes rebounded, corporate execs brimmed with confidence, and dealmakers got their mojo back. The latter half of the 2010s has produced some of the frothiest years for global M&A in history, with each of the last five years generating more than $3 trillion in global announced deal volume, according to Bloomberg data.

Along the way, different trends helped propel dealmaking. In the early 2010s, corporate inversions to save on taxes were the rage - up until the US government put the kibosh on such deals in 2014. Activist investors have grown in prominence and influence, kicking up dust and maneuvering for deals across the world.

And the rise of tech giants throughout the decade, and the influence of technology across industries, has spurred waves of transactions from companies willing to pay up to gain an edge or, in some cases, stave off their own obsolescence.

Business Insider spoke with M&A bankers, lawyers, and academics to determine 10 of the most significant deals of the decade.

While some of the largest deals of the 2010s appear on this list, this is not a list of the largest deals of the 2010s.

Some acquisitions that may have seemed small and inconsequential at the time have grown weighty in retrospect, like Facebook's acquisition of Instagram for a mere $1 billion. Or, in the case of Amazon's $13.7 billion deal for Whole Foods, the very nature of an unexpected buyer threatened to upend an entire industry and put management teams across America on notice that the same could happen to them.

For this project, we reviewed and included deals from a variety of industries, though we didn't consider deals that have not closed or received regulatory approval.

Here are 10 of the most significant mergers and acquisitions of the decade that made history, transformed industries, and made a lasting impression in the world of dealmaking.