Fastjet shares plunged more than 17% on Tuesday as the low-cost airline reported widening losses for the first half of the year.
The company, which offers budget flights across a number of African countries, said operating losses deepened to 31 million US dollars (£23.8 million) in the first six months of 2016, compared with losses of 12.8 million US dollars (£9.8 million) reported a year earlier.
"The trading environment in which fastjet operates remains challenging. Consequently and as previously announced, the group is expected to continue to be cash flow negative and report a substantial operating loss for the full year," fastjet said.
Its AIM-listed shares slumped as much as 17.8% or 4.5p to 20.8p following the earnings release.
The airline's cash balance plummeted to 3.8 million US dollars (£2.9 million) as of June 30, from 71 million US dollars (£54.4 million) in June 2015.
Group revenue "only marginally increased" in the six months to June 30, "while capacity has doubled and load factors also remain disappointing", fastjet said.
Revenue rose to 33.1 million US dollars (£25.4 million) from 31.5 million US dollars (£24.1 million) a year earlier.
The company's half-year results also raised the possibility that the company could go under, due to "material uncertainties" including passenger numbers, unhedged fuel prices and adverse currency exchange rates
"The matters described above represent material uncertainties that may cast significant doubt upon the group's and the parent company's ability to continue as a going concern and, therefore, to continue realising its assets and discharging its liabilities in the normal course of business," the firm said.
However, fastjet tried to reassure investors by saying it "remains confident" that the implementation of its stabilisation plan will "materially improve" the company's financial performance in the medium term.
It will include moving fastjet's headquarters from Gatwick to Johannesburg, South Africa, in a bid to cut costs and be closer to home markets, newly-appointed chief executive Nico Bezuidenhout explained.
The company will also reduce its fleet of A319 aircraft from five to three by year-end, to be replaced by three smaller leased aircraft that Mr Bezuidenhout said will cut down seat capacity and trip costs by around 15%. Routes and schedules will also be reviewed.