(Reuters) - Sears Holdings Corp, once the largest U.S. retailer, warned on Tuesday about its ability to continue as a going concern after years of losses and declining sales.

"Our historical operating results indicate substantial doubt exists related to the company's ability to continue as a going concern," Sears said in its annual report for the fiscal year ended Jan. 28. (bit.ly/2mRUcce)

The company said an inability to generate additional liquidity might limit its access to new merchandise or its ability to procure services. Continued operating losses also could restrict access to new funds under its domestic credit agreement, according to the filing.

The warning comes less than six weeks after the company announced what it called the “next phase of its strategic transformation,” in which it hoped this year to reduce costs by $1 billion and cut its debt and pension obligations by at least $1.5 billion.

Sears shares were down 17.6 percent in premarket trading on Wednesday.

The company is also considering selling some of its businesses, such as the Kenmore appliances and DieHard car battery brands.

The Sears catalog was an emblem of the post-World War II consumer boom in the United States but the company was unable to adjust to the changing retail landscape and rising competition from Wal-Mart Stores, Target Corp and others.

FILE PHOTO - A Sears logo is seen inside a department store in Garden City, New York, U.S. on May 23, 2016. REUTERS/Shannon Stapleton/File Photo

The company lost $2.22 billion in the year ended Jan. 28.Since 2013 it has accumulated $7.4 billion in losses and seen revenue fall 44 percent to $22.1 billion.

During that time, Sears cut the number of its U.S. stores by nearly a third, reduced holdings in Sears Canada, and spun off the Lands’ End clothing chain.

Its total liabilities stand at $13.19 billion.

In recent years, Sears has placed some of its stores into a real estate investment trust (REIT), sold its Craftsman line of tools, and repeatedly raised debt from billionaire Chief Executive Edward Lampert’s hedge fund.

Lampert owned nearly 10 percent of the REIT that paid Sears $2.6 billion in 2015 for stores that it purchased, many of which were then leased back to the retailer.

The announcement of Sears’ potential demise is a blow to Lampert, a hedge fund investor who took control of Sears after merging it with Kmart, which he controlled, in 2004.

He soon published a 15-page manifesto, in which he stated that conventional measures of retail success, such as same-store sales, were no longer relevant. Sears would regain its health by closing struggling stores and focusing instead on profitable sales, he wrote.

Sears last turned an annual profit in 2011.

Sears said on Tuesday actions taken during the year to boost liquidity, including the $900 million sale of the Craftsman tool brand to power tool maker Stanley Black & Decker Inc early this year, could satisfy its capital needs for the current fiscal year.

But the filing also makes clear that additional asset sales could prove problematic.

As part of the Craftsman sale, Sears Holdings reached an agreement with the Pension Benefit Guarantee Corp. That puts a claim on some Sears’ assets in an effort to protect pensions of retired employees.

The agreement “contains certain limitations on our ability to sell assets, which could impact our ability to complete asset sale transactions or our ability to use proceeds from those sales to fund our operations,” the company said.

Already, the pension board agreement requires Sears to make a $250 million cash payment to its pension plan by March of 2020, and the pension board has a 15-year lien on revenue owed to Sears from future sales of Craftsman products.