Bayer → Monsanto
Bayer's $66bn cash takeover of Monsanto, agreed in September 2016 and completed in June 2018, was the largest acquisition ever made by a German company and made Bayer the owner of Roundup — and of the cancer lawsuits over it that weighed on the group for the following eight years.
At $128 a share the largest all-cash acquisition on record; glyphosate litigation later drove Bayer's market value below the price paid.
- Value
- $66B
- Announced
- September 2016
- Completed
- June 2018
- Sector
- Agriculture
- Deal type
- acquisition
- Acquirer
- Bayer (Germany)
- Target
- Monsanto (United States)
Why it mattered
Monsanto was the world's biggest seed supplier, with 26% of the global market in 2015, a major producer of genetically engineered crops and the maker of Roundup, a glyphosate weedkiller. Bayer, which had spun off its materials business as Covestro to become a life-sciences company, wanted to combine its crop-protection business with Monsanto's seeds.
Monsanto rejected Bayer's first approach in May 2016, worth about $62bn. The agreed price, $128 a share in cash, was a 44% premium to Monsanto's share price before that approach and gave the deal an aggregate value of $66bn. Bayer expected about $1.5bn a year of synergies after year three, arranged $57bn of bridge loans, planned about $19bn of equity through mandatory convertible bonds and a rights issue, and offered a $2bn reverse break fee if antitrust approval failed.
Approval took almost two years. The European Union cleared the deal on 21 March 2018, and on 29 May the US Justice Department required Bayer to sell businesses worth about $9bn — including its canola, soybean and vegetable seeds and its Liberty herbicide — to BASF, which it called the largest merger divestiture it had ever required. The purchase closed on 7 June 2018, and Bayer dropped the Monsanto name.
What it left behind
Two months later a US jury awarded $289m to a groundskeeper who blamed Roundup for his non-Hodgkin lymphoma, and Bayer's shares fell by about 14%. The award was cut on appeal, but claims multiplied; in June 2020 Bayer agreed to pay up to $9.6bn to settle most of them, and by 2023 its market value had fallen more than 60% since the merger, to less than half of what it paid for Monsanto. In February 2026 Monsanto proposed a nationwide class settlement for current and future claims, and on 25 June 2026 the US Supreme Court ruled 7–2 that federal pesticide law pre-empts state failure-to-warn claims, which Bayer says make up the vast majority of the litigation. In July 2026 Bayer said it would consolidate its US glyphosate business in a separate subsidiary, Ruveon. Due diligence on a target's flagship product has to price the courtroom as well as the market: the liabilities attached to Roundup, more than the strategic fit, shaped Bayer's returns.