European stocks hit a 3-week low on Friday at the end of a busy week as investors worried about the impact of fresh U.S. levies on dozens of countries including a 39% rate on Switzerland.

On the day, healthcare stocks dropped 1.3% after U.S. President Donald Trump sent letters to the leaders of 17 major pharmaceutical companies including Novo Nordisk (NYSE:NVO) and Sanofi (NASDAQ:SNY) outlining how they should slash U.S. prescription drug prices.

Novo Nordisk shed 4.2%, falling to an almost three-year low, while Sanofi shed 1%.

The pan-European STOXX 600 index fell almost 1% by 0720 GMT, down for the third straight session and on track to end the week in red.

The benchmark index has slipped 4.4% from its Monday peak, when it came within 1.8% of its March all-time high, dragged down by a record plunge in Novo Nordisk shares following a profit warning, and as investors assessed the implications of the U.S.-EU trade deal.

Trump continued his tariff blitz, announcing steep levies on exports from dozens of trading partners including Canada, Brazil, India and Taiwan with countries not listed subject to a base 10% rate ahead of a Friday trade deal deadline.

Germany blue-chip DAX shed 1.1% while Denmark’s OMXC fell 2.8% to a nearly two-year low. Most regional bourses were in the red.

Among individual stocks, Italy’s Campari (LON:0ROY) was the top gainer on the STOXX 600 index, adding 8.6% after reporting an increase in second-quarter operating profit.

British Airways owner IAG gained 2.1% after reporting better-than-expected quarterly earnings on continued demand for transatlantic routes.