In order to meet regulatory requirements, Bayer has agreed to sell business units with combined revenue of 2.2 billion euros to German rival BASF for 7.6 billion euros.
Bayer's shares were the worst-performing in the DAX stock index in early Monday trading, reflecting concerns amongst investors that the court ruling could spark further legal action shortly after the Leverkusen-based completed its 63-billion-dollar takeover of Monsanto in June.
Bayer shares plunged the most in nearly seven years after Monsanto was socked with US$289 million in damages in the first trial over claims that the herbicide causes cancer. Sign-up now and enjoy one (1) week free access! Bayer denies that glyphosate causes cancer when used correctly.
Two months after clinching its US$66 billion purchase of Monsanto Co., Bayer AG faces a protracted legal battle over the USA company's Roundup weed killer - a prospect that wiped more than US$11 billion off the German conglomerate's market value.
It said other court proceedings with other juries might "arrive at different conclusions" than the jury which ruled in the California lawsuit, the first to accuse glyphosate of causing cancer.
"We will appeal this decision and continue to vigorously defend this product, which has a 40-year history of safe use and continues to be a vital, effective and safe tool for farmers and others", Monsanto Vice President Scott Partridge said.
Monsanto has long argued there is no proof glyphosate is carcinogenic, citing a report conducted by the Environmental Protection Agency's (EPA) Assessment Review Committee that says the chemical is "not likely to be carcinogenic to humans" as well as "hundreds of studies" conducted around the world that show glyphosate's safety.
Glyphosate, the main ingredient in Roundup, was first approved for use in Monsanto's weedkiller in 1974.
Johnson's attorneys sought and won $39 million in compensatory damages and $250 million of the $373 million they wanted in punitive damages. Doctors diagnosed him in 2014 with non-Hodgkin's lymphoma.
"Monsanto made a choice to not put a cancer warning on the label", Mr Wisner said. The German company is due to begin integrating Monsanto's operations into its own later this month. Johnson's case was fast-tracked to trial given the severity of his condition and his grave prognosis. Johnson declined to take questions from reporters.
This article was written by Joel Rosenblatt, Robert Burnson and Naomi Kresge, a reporter for The Washington Post.