WuXi AppTec Co. tumbled after a US Senate committee advanced a bill that may ban Chinese biotech firms from accessing federal contracts and cut off the company from the market that generates more than half of its revenue.
WuXi AppTec plunged as much as 21%, while its sister company WuXi Biologics Cayman Inc. dropped 20%. Both stocks have lost more than 40% so far this year, making them the worst performers on the benchmark Hang Seng Index.


