Shionogi & Co. slumped the most in more than a decade after the drugmaker said animal studies showed its experimental Covid drug disturbed fetal development. The stock fell as much as 16% in Tokyo trading Wednesday, the biggest intraday decline since March 2011. The stock had been down 8.4% this year through April 12.

The drug likely won’t be recommended for pregnant women, Kyodo News reported Tuesday, April 12, without giving attribution. The animal data, which showed harm when it was given at high doses, was submitted to Japanese regulators in February when the company sought a review, a Shionogi spokesman said. The pill’s chances of success fell to 5% from 50% after the report tying it to birth defects, Stephen Baker, an equities analyst at Jefferies & Co., wrote in a note to clients. He cut his rating on the stock to “underperform” from “buy” on Wednesday after trimming the profit estimates and target price. Still, rival Covid treatments also carry risks for pregnant women but have been approved for use. Merck & Co.’s Lagevrio has a boxed warning saying it shouldn’t be taken by pregnant women after it was linked to fetal harm in animal studies. Pfizer Inc.’s Paxlovid at high doses led to a decrease in fetal body weight in a rabbit study, though there aren’t restrictions on its use during pregnancy.     Source: Bloomberg