Shares in American Airlines parent AMR have fallen by more than a third in the past 24-hours as the embattled carrier faces questions over its future.

To date, American is the only large US carrier not to have sought temporary refuge in Chapter 11 bankruptcy protection – a decision which increasingly looks like a liability.

Yesterday the Fort Worth-based carrier was forced to deny, once again, that it would seek bankruptcy protection against mounting losses.

In a statement, AMR said there was, as yet, “no company-driven news that caused the volatility” in stock market prices, instead blaming “rumours and speculation” for the falls.

At this stage bankruptcy “is certainly not our goal or our preference” AMR added.

“We know we need to improve our results, and we are keenly focused as we work to achieve that.”

However, markets remained sceptical, with shares in AMR falling as low as $1.75, giving the company a capitalisation of just under $700 million.

Avoiding bankruptcy early last decade has hamstrung American since, with an aging, fuel inefficient, fleet pushing up already high fuel costs.

Cumbersome labour costs have also proved debilitating to the carrier.

American has recently been trying to renegotiate its labour contracts in order to cut costs, but this has proved ineffective.

As a result, American is on course to deliver a fourth annual loss this year, adding to $12 billion in losses seen over the past decade.

However, the company does have over $4 billion in unrestricted cash, which should allow it to fend off any bankruptcy decision for a time.

Moody’s Investors Service last month changed its outlook to negative from stable on the company’s debt - which totalled $17.1 billion as of June 30th.

The ratings agency cited expectations of deteriorating liquidity, weak operating performance and uncertainty about the company’s ability to achieve a better cost structure.