Bayer bought Monsanto for $63B — then Roundup lawsuits destroyed €100B in market value

Bayer, the German pharmaceutical and life sciences company, agreed to acquire Monsanto in September 2016 for $66 billion. The deal closed on 7 June 2018 after regulatory approval. It was the largest acquisition by a German company in history. Bayer retired the Monsanto brand and integrated the business into its crop science division. The strategic rationale was to create a global leader in agriculture and seeds.

Two months after the deal closed, a San Francisco jury ordered Bayer to pay $289 million to Dewayne Johnson, a school groundskeeper who claimed Roundup caused his non-Hodgkin's lymphoma. The verdict was the first of thousands. By 2023, approximately 165,000 claims had been made against Bayer over Roundup. The company lost several high-profile trials, with verdicts reaching $2.5 billion (later reduced on appeal).

In June 2020, Bayer agreed to pay up to $10.9 billion to settle the majority of claims, but tens of thousands remained pending. Bayer's stock lost 46% of its value within ten months of the acquisition and over 60% by 2023. The company warned in 2025 that it might need to file Chapter 11 bankruptcy for its Monsanto division. The Bayer-Monsanto deal is now considered one of the worst corporate acquisitions in history.