On the Beach recorded a first-half loss of £34 million in the six months to the end of March, compared to a profit of £12 million for the same period last year.
The reversal in fortunes was pinned on the sharp slowdown in travel following the Covid-19 pandemic.
Revenue slumped by two thirds over the period, to £21 million.
The company did not declare an interim dividend.
The bleak result included exceptional costs of £35 million, which the company said represented the estimated cost of Covid-19 to trading in the first half.
The online travel agent said booking volumes for summer 2021 remained low, but were significantly ahead of the prior year.
This was due in part to the early release of flights for next year by most major airlines, a statement added.
“In the aftermath of the Thomas Cook collapse, the group made excellent progress in the first four months of the financial year, driving record levels of brand awareness and achieving sales growth of almost 30 per cent for holidays departing in summer 2020,” Simon Cooper, chief executive of On the Beach Group explained.
“We also made significant progress against our strategic objectives in the year with classic package holidays going live in over 2,600 agencies…