Travel stocks have been hit harder than most amid the rapid spread of the coronavirus epidemic, and, within that sector, airline stocks have suffered the most.
It is yet another blow to an industry that has been hamstrung for much of the past year by the grounding of Boeing’s 737 Max – the workhorse of many fleets worldwide.
That had forced airlines, including Ryanair, to lower their ambitions for expansion of routes and passenger numbers as ordered aircraft didn't arrive.
The latest crisis presents a different concern: there are enough planes but many will have to be diverted as passengers shy away from travel to an increasing number of destinations. It is being exacerbated by the cancellation of a growing number of headline business conferences and events – including Mobile World Congress in Barcelona and the Geneva Motor Show.
Aer Lingus parent IAG was the latest company to tell markets on Friday that the spread of Covid-19 meant it was no longer able to give any accurate guidance to investors on what to expect from the company in financial terms this year.
The group, which includes British Airways, Iberia and Vueling, is reducing capacity, citing "demand weakness on Asian and European routes and a weakening of business travel across our network".
European rival Lufthansa has said that it will cut flights on both long and short-haul networks while staff at Europe's other big beast, Air France-KLM, were told in a video by chief executive Ben Smith that it was readying a new round of cost-cutting to deal with the "extraordinary situation".
Budget carriers have not escaped, with EasyJet announcing plans to reduce capacity on some routes, though Ryanair is still insisting that it is business as usual – for now.
The scale of the challenge for airline executives was highlighted by the commendably understated view from American airline United last week when it said demand for flights to China was down "approximately 100 per cent".
Airline chiefs are well used to dealing with disruption, whether through weather, terror attack or economic collapse. Their biggest problem this time is lack of visibility on when things might get back to anything approaching normal.