Bayer's $66B Monsanto buy made it seeds-and-pesticides king — and a litigation hostage

In May 2016 Bayer offered $62B in cash for Monsanto and was rebuffed; in September it raised the offer to $66B — $128 a share, a 45% premium — the largest all-cash acquisition ever attempted. The logic was adjacency: pharma meets seeds and pesticides, with the combined company controlling more than a quarter of the world's supply and becoming the biggest seed and pesticide group.

The deal closed on 7 June 2018 after EU and US clearance, and the Monsanto name disappeared. The hidden cost surfaced over the next two years: Roundup (glyphosate) cancer litigation. In June 2020 Bayer agreed to pay more than $10 billion — about $9.6B for some 125,000 existing non-Hodgkin lymphoma claims, plus $1.25B for a future-claims fund — in one of the largest product-liability settlements of its kind.

The market had begun pricing the risk on day one: Bayer's shares slid toward a 2.5-year low on the 2016 announcement and never regained their multiple. By 2024 a new CEO was weighing a break-up — selling consumer health or crop science, or splitting three ways — after a €4.57B quarterly loss driven by crop-science writedowns. The deal is now a textbook case of acquisition risk mispriced as future, not present.

Over 25% of the world's seed and pesticide supply — plus Roundup's litigation: $10B+ settled by 2020 and a break-up debate by 2024

The due-diligence failure was in the liability file: most Roundup claims came after closing, but their existence was knowable in 2016 — the deal's optionality included a litigation book.

Scale in agriculture was real but unintegrated: the seed-pesticide combination was strategically sound, yet the market discounted the group for years because the balance sheet carried the war.

All-cash removed the market's veto: funding history's largest cash bid without an equity vote concentrated the litigation gamble on the company alone.

Before an all-cash megadeal, price the hidden liabilities as if they were already yours: the acquired risk is not past or future — it is in the room the day you sign

Bayer remained a litigant for years, settling further claims while contesting the rest, as investors pushed for a break-up from 2023-2025. The Monsanto purchase is regularly cited among the most value-destructive acquisitions of the era.