Aberdeen-based bus and train operator FirstGroup has warned it faces an uncertain future after coronavirus caused a collapse in passenger numbers.
The warning came as the firm announced annual losses of more than £150m.
Coronavirus saw average passenger numbers fall by 90% in March alone.
First warned about its ability to continue as a going concern - a fully-operating, profit-making business - although it said there is enough funding to get through the next year.
The operator is pinning its hopes on a return of passengers as lockdown restrictions are eased further and people get back to work, school and social events.
The loss of £152.7m followed a 2019 profit of £9.8m. First shares fell sharply on the news on Wednesday morning.
First runs bus services in most of the UK's biggest towns and cities, as well as services in the United States.
The company said its first priority was the health and safety of passengers and employees, and it was "immensely proud" of efforts.
Trading trends prior to the pandemic were said to have been "broadly similar" throughout the year.
Chief executive Matthew Gregory said: "There is no way of predicting with any certainty how the coronavirus pandemic will continue to affect the public transportation sector and the impact it may have on customer trends longer-term.
"However, as leading operators in each of our markets we are strongly positioned for a recovery in passenger demand and for the opportunities that may emerge from this exceptional period.
"Despite the near-term uncertainty, the long-term fundamentals of our businesses remain sound."
He added: "The importance of public transport to society has never been more clearly demonstrated.
"We will continue to take all necessary measures to enable the group to emerge from this unprecedented situation in a robust position."