Updated from 11:25 a.m.

AMR ( AMR) shares slumped Friday amid news that American Airlines will reimburse creditors and suppliers with 3 million shares of common stock, in exchange for concessions that will save the company $175 million annually.

"We are grateful to each supplier, lessor and creditor who tangibly expressed support for our company by granting these significant concessions," said Chief Executive Gerard Arpey.

While the $175 million in concessions represents the final step in the company's goal of hacking costs by $4 billion annually, the company reminded investors that it is not out of the woods yet.

"We continue to move through the most challenging period in our history, and our success is still far from assured," said Arpey. "But reaching these cost-reduction agreements with our suppliers, lessors and creditors is another step forward and further strengthens AMR as we seek to put the company on a solid financial footing."

The comments put cold water on a rally in AMR stock. After jumping more than 60% since unions agreed to cost cuts that helped the company avert bankruptcy on April 25, shares were down 6.6% at $6.28 on Friday, following Thursday's drop of 4.5%.

While some on Wall Street, like UBS Warburg analyst Sam Buttrick and Blaylock & Partners analyst Ray Neidl, have said the cost cuts and industry recovery will keep AMR from filing for Chapter 11, others were less confident.

"The company's statement about the risk of bankruptcy is accurate," said Clark Orsky, a bond analyst for KDP Investment Advisors. "They've gotten concessions from unions, lessors, and that improves prospects in the near term; nevertheless, they have a rather large debt load and they've got a lot of overlap with low-fare carriers. They've got cost cuts, but they need to see recovery in revenue side of equation."

With many airline stocks having doubled or tripled in value over the last couple months, analysts have begun warning that the rally could have peaked and investors should take profits. Furthermore, some have warned that much of the surge has been due to of short covering, since short interest in AMR shares quadrupled prior to the recent rally.

"We believe that AMR's long-term viability will depend in part on how much positive cash flow the company can stash away before the cold winter period," said William Greene, airline analyst for Morgan Stanley. "If the company begins September with an insufficient cash balance, we believe market participants will again focus on liquidity questions at the company in the fourth quarter."

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