NEW YORK (AP) — Shares of Sears Holdings fell Tuesday, a day after the retailer announced that chairman and hedge fund billionaire Edward Lampert will take over the role of CEO.

The investor queasiness came even as the Hoffman Estates, Ill.-based company offered an update on holiday sales that showed some improvements at its Sears stores. Overall, the company still faces a long, uphill battle to turn itself around.

Lampert succeeds Louis D'Ambrosio, who is leaving February because of family health matters. D'Ambrosio, who will remain on the board until the company's annual meeting in May, was named CEO in 2011.

Lampert has been known as a hands-on chairman at the operator of Sears and Kmart. The change formalizes that role at a time when the retailer is struggling with sales declines and losses.

"At the end of the day, there is only one person who makes the big decisions... and that person is Mr. Lampert," said Gary Balter, an analyst at Credit Suisse, in report. "Giving him an additional title does not change that reality, and in our opinion, does not change the direction of the company."

In a statement, Lampert said that he plans to continue to build on the steps outlined last year to get the company back on track.

"I have agreed to assume these additional responsibilities in order to continue the company's recovery and sustain the momentum we are experiencing," said Lampert, the company's largest shareholder. "Working closely with the board, management and our dedicated associates, we will remain focused on executing our goals, improving operations and building sustainable long-term value for shareholders."

Lampert has a tough road ahead. He engineered the combination of Sears and Kmart in 2005, about two years after he helped bring Kmart out of bankruptcy.

The company has posted six straight years of declines in revenue at stores opened at least a year. While Sears' middle-income shoppers has been hit hard by the economy's woes, critics have long said the company hasn't done enough to invest in its stores to compete with Wal-Mart Stores Inc., Target Corp. and other competitors.

Last year, Sears announced plans to restore profitability by aggressively cutting costs, reducing inventory, selling off some assets and spinning off others. Under D'Ambrosio,who spent 16 years at IBM Corp., Sears has been making changes in its stores. They include giving sales staff almost 15,000 iPads and iPod Touch devices so they can research products and help customers check out wherever they are in a store. It's also improving displays and adding more high-tech washing machines and other appliances. The company is also focusing on a loyalty program, which now accounts for more than half of the company's revenue.

Such changes have helped the business, but analysts say much more needs to be done.

Sears said Monday that in the nine-week period ending Dec. 29, revenue at stores open at least a year fell 1.8 percent, largely due to sales declines in consumer electronics at both Sears and Kmart. The period included the crucial holiday season, when retailers can make up to 40 percent of annual revenue.

But revenue at stores open at least a year at its Sears stores has risen 0.5 percent so far this quarter. That would mark the first quarterly increase since the first quarter of 2010, when a federal cash-for-appliance program started, boosting sales.

Revenue at stores open at least a year is a key metric for retailers because it excludes revenue at stores that recently opened or closed.

Sears also gave an update on its fiscal fourth-quarter earnings. It said it expected a loss between $2.64 and $3.40 per share for the quarter ending Feb. 2. Excluding one-time items, it forecasts a profit of between $1.25 and $2 per share. The company is expected to report final fourth-quarter and full-year results on Feb. 28.

"The bottom line imperative for (Sears) is that it needs to stabilize traffic in the domestic operations if it will remain viable for the duration," Greg Melich, an analyst at the International Straregy & Investment Group LLC, said in a report released Tuesday.

Balters said uncertainty at rival J.C. Penney highlights another big problem: Sears could lose whichever direction Penney goes. Since Penney started a new pricing plan on Feb. 1 that eliminates hundreds of sales events in favor of everyday lower prices, the company has seen sales fall dramatically. Balters reasons that if Penney returns to discounting, it may take back some lost market share at lower prices, hurting Sears' clothing sales. He believes a bigger problem for Sears would be further deterioration of the Penney franchise. If Penney starts closing locations, that could undermine the value of Sears' real estate holdings, he wrote.

Brian Sozzi, chief equities analyst at NBG Productions, wonders whether Lampert will now just focus on selling off more assets instead of fixing the business.

"Will any of the signs of life at (Sears) continue to be nurtured?" he asked.

But Chris Braithwaite, spokesman at Sears, emphatically said Lampert will focus not just on the financial performance but on the customer experience. Improving stores is just as important as generating cash, he noted.

Sears operates more than 2,600 stores in the U.S. and Canada.

Shares of the Hoffman Estates, Ill.-based company fell $2.50, or nearly 6 percent, to $40.42 in trading Tuesday. In the past 12 months, they have risen almost 58 percent.