The carrier ended up with a second-quarter operating loss of 863 million crowns. That translated into a net profit of 1 billion thanks only to its 17.5 percent stake in Norwegian Finans Holding (NOFI.OL), a bank it launched to offer customers credit and to run its loyalty program.

One banker who declined to be named said the performance was the result of “increased interest expenses, huge capital expenditure, yields under pressure and aggressive commercial growth based only on market share versus profitability.

The banker said he stopped looking at potential financial exposure to Norwegian Air one to two years ago, partly because the airline did not have enough capital backing its expansion.

Norwegian’s ability to meet its short-term debt obligations is ranked second-worst among European carriers after Croatia Airlines HRAR.ZA, according to Thomson Reuters Eikon data.

Norwegian’s so-called quick ratio, a commonly used indicator of short-term liquidity, is 0.42, less than half the average of regional rivals. Its interest coverage ratio, a measure of how easily it can service outstanding debt, is just 3.2 while the ratio for Ryanair is 25.2. “What gets me with Norwegian ... is the balance sheet could be better. It is so low on equity, so high on debt, it would be safer if they had a bit more equity behind it,” said James Halstead, a managing partner at consultancy Aviation Strategy.