The shares of Thomas Cook continued to fall on Tuesday and have now plummeted by almost 60% in eight days.
The bonds of the travel company also lost value and the cost of securing its debt against payment default reached a record level.
Concerns about his loans increased last week when he issued a second profit alert in two months and said earnings would be £ 30 million less than expected.
Last week, the company said it had not violated its banking arrangements.
Towards the end of Tuesday morning, the company's stock market value had fallen to £ 363 million, routing it to be downgraded from the mid-cap FTSE 250 stock index.
The figure is lower than the company's last published net debt of £ 389 million.
"The debt itself, when the operating performance was quite as good as last year, was adequate," said Leandro de Torres Zabala, senior director at the S & P Global credit rating agency .
"When operational performance weakens, of course, on a proportional basis, the debt becomes higher."
Last week, Thomas Cook's managing director, Peter Fankhauser, admitted that it was a "disappointing year" for the travel company.
The company has accused its fall in profits on the prolonged summer heat wave, which has led to a decline in bookings.
He also said that his bookings for this winter fell 3% from last year and have suspended his dividend.