Lufthansa is grounding planes and canceling flights as the coronavirus outbreak spreads in Europe.

The German airline said Thursday it has canceled 7,100 European flights for March, mostly within Germany or on routes to Italy, accounting for about 25% of its total capacity.

Investors have punished airlines stocks in recent weeks. United Airlines stock is down 32% so far this year, for example, and shares in Germany's Lufthansa are down 29% over the same period.

Earlier this week, Lufthansa said it would ground 150 of its 770 aircraft.

"Guests who have submitted their contact details to Lufthansa will be proactively informed of the cancellations," the company said in a statement.