(Bloomberg) -- AbbVie Inc. peeled off about $20 billion in market value after a critical new medicine for arthritis faced a major setback. 

Rinvoq, which already carries the U.S. Food and Drug Administration’s most stern warning, a so-called black box on the immune therapy’s label, will now add new warnings that the drug carries an increased risk of blood clots and death. AbbVie shares plunged as much as 12%, the biggest drop since March 2020 after the agency’s update. 

The unexpected warning come after tests of Pfizer Inc.’s Xeljanz, a similar drug, showed increased risks. Xeljanz and Eli Lilly & Co.’s Incyte Corp.-partnered drug Olumiant will carry similar warnings as Rinvoq. AbbVie’s stock was hit particularly hard as Rinvoq is supposed to be the company’s next big drug as the top-selling Humira comes off patent and future sales taper. 

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