Interstate Bakeries Corp., the maker of Wonder Bread and Hostess Twinkies, hired turnaround firm Alvarez & Marsal after it again delayed filing its annual report with American regulators. The shares fell more than 42%.

Interstate said in a statement that it will file the report for the year ended May 29 after it resolves “a number of recently identified interrelated circumstances.”

If it doesn’t file the document by September 26, it may not be able to borrow further from its lenders, Interstate said.

The largest American wholesale baker in March suspended its dividend and began closing plants as a changing American diet cut demand for carbohy drate-rich breads and cakes.

The company might have to file for Chapter 11 bankruptcy protection, a Credit Suisse First Boston analyst, David Nelson, wrote in a research note. Such a move might include selling assets.

“The company continues to be in financial difficulty as it has been for many months now,” Mr. Nelson wrote. “We continue to believe that neither Interstate’s lenders nor their unions want to own baking plants, but that possibility exists.”

Mr. Nelson doesn’t own the shares, nor does the company have an investment banking relationship with Interstate.

Interstate shares fell $3.34 to $4.56 in New York Stock Exchange composite trading. Earlier the shares reached $5.02.The stock has fallen 45% this year.

Interstate said sales continued to slow in the first quarter, though a new financial-reporting system made analysis “difficult,” and it may not be in compliance with a senior secured credit facility.

As a result, the annual report may contain a note from Interstate’s independent auditors stating that there might be “substantial doubt” about Interstate’s ability to “continue as a going concern,” the Kansas City, Mo.-based company said in a statement.

Alvarez & Marsal is a New York based company that helps corporations struggling to avoid or emerge from bankruptcy.

They include HealthSouth Corp., the largest American operator of physical therapy hospitals; Spiegel Inc., owner of Eddie Bauer stores; and National Century Financial Enterprises.

An analyst with D.A. Davidson & Co., Tim Ramey, lowered his rating on Interstate to “neutral” from “buy.”

“While we still maintain that IBC is a likely acquisition target, we are unable to determine what we believe the true value of the corporation to be,” Mr. Ramey wrote in a research note. “The company still has good book value and cash flow, is in an improving mode, and we expect that IBC’s new management team is capable of managing through the company’s difficulties.”

Mr. Ramey doesn’t own Interstate shares, said Mr. Ramey’s research associate, Benjamin Cooper.

In late July, Interstate said the SEC started an inquiry after the company hired attorneys to review the workers’ compensation reserves. Interstate said the SEC review is informal.

On August 11, the company asked for a filing extension to August 27 to restate earnings for its fiscal second and third quarters to reflect a $40 million charge for expenses related to workers’ compensation insurance.