AstraZeneca shares fell by 8% at the close of trading on Tuesday, marking the British-Swedish pharmaceutical company’s worst daily stock decline since March 2020.

Report informs via Reuters that the investor pessimism stems from news of a Chinese government investigation into AstraZeneca’s local business leaders. Last week, the drugmaker itself reported that the head of its Chinese division, Leon Wang, was under investigation and that the company would cooperate with Chinese authorities. However, no further details were provided at the time.