For years, Facebook and other large technology companies grew into vast digital conglomerates by making so-called killer acquisitions, small deals for companies that could one day pose a competitive threat.

Internal emails between executives at Facebook show Chief Executive Officer Mark Zuckerberg and his executive team were quaking at their keyboards in 2012 as they watched WhatsApp grow to dominate the market for messaging apps and "become the biggest threat we’ve ever faced.” Two years later, Zuckerberg swooped in with a $19 billion offer that was too good for WhatsApp’s founders to refuse.

But those days are done. Even acquisitions of smaller companies, including Facebook’s $315 million purchase of Giphy, a GIF search tool, in 2020, are now under threat of being unraveled. Just recently, the U.K.’s antitrust watchdog ordered Facebook’s newly branded parent Meta Platforms Inc. to sell Giphy, marking the first time a global regulator has forced a large technology company to reverse a completed deal. Facebook has said it will appeal the decision.