Peterborough-based travel operator Thomas Cook has plunged into the red with losses totalling £163 million.
The holiday giant, which employs more than 1,000 people at Westpoint, Lynch Wood, has blamed the prolonged hot weather in Europe, unexpected charges and discounting for its losses.
Chief executive Peter Fankhauser said: "2018 was a disappointing year for Thomas Cook.
"Looking ahead, we must learn the lessons from 2018 and go into the new year focused on where we can make a difference to customers in our core holiday offering."
Its annual results for the year to the end of September, show that while the company's revenue rose by six per cent to £9.6 billion it still made a loss after tax of £163 million compared to a £9 million profit the previous year.
The company's debt has also widened from £40 million to £389 million.
It has also scrapped dividend payments to shareholders.
The company's share price slipped by one per cent following the release of its results.
Earlier this week, the company took investors by surprise by issuing a profits warning just a few days ahead of the publication of its annual trading figures.
It was the company's second profits warning in two months.
Mr Fankhauser said: "After a good start to the year, we experienced a larger-than-anticipated decline in gross margin following the prolonged period of hot weather in our key summer trading period.
But he added: "We have achieved some important milestones in our strategy for transforming the business."