Eddie Lampert might be losing some support for his strategy at Sears Holdings Corp.

Bruce Berkowitz, the largest outside shareholder of the company who has long supported Lampert, may be taking more of an activist role. Berkowitz’s Fairholme Capital Management disclosed in a filing on Tuesday that it has bought an additional 390,100 shares since Christmas Eve and now owns a 26.02 percent stake in the retailer, or 27,763,748 shares.

The only other shareholder with a bigger stake is Lampert, the chief executive officer who owns 30,670,247 shares or 28.75 percent. The third-largest shareholder is Lampert’s ESL Investments with a 20.94 percent ownership stake.

Berkowitz has said before that he was impressed with Lampert’s behavior, but apparently that has changed. Fairholme stated in a filing on Dec. 18 that it will be in touch with Sears management and the board as well as other significant shareholders regarding its views on Sears’ long-term prospects. At the time of that filing, Fairholme’s stake totaled 24.9 percent, or 26,603,248 shares.

On Fairholme’s Web site, describes Sears as “a real estate behemoth in retailer’s clothing.” The manager also wrote that Sears “remains our proverbial beach ball held under water.” For now, it seems that the stock remains under water since the shares lost 38 percent of their value in 2015.

Back in February, Berkowitz said on a conference call, “The real estate within Sears is a unique position. It’s a once in-a-lifetime opportunity you cannot re-create. I really don’t understand the market’s ignorance as to the values within Sears. But, then again, I keep [reminding] myself that, yes, most people once thought that the world was flat.”

Berkowitz was asked on that call whether the retail losses would eat up the real estate value and he said, “The retail losses will stop with either success or failure. Of that, we’re highly confident and, in fact, the company in the last quarter stated that the trends are turning for the better.”

Unfortunately, on Dec. 3, things took a turn for the worst as Sears revealed a $454 million third quarter loss. On that day, Fairholme bought 418,500 shares at $18.90 and has continued to buy shares almost every day in December.

Rather than retail sales, Berkowitz is mostly interested in the real estate and suggested that Sears could have the largest commercial real estate portfolio in the U.S. He said on the February call, “We [go] property by property, we’ve hired professional surveyors, we have our in-house evaluations, we’ve used sampling and statistical techniques, competitor analysis with Simon, GGP, Macerich, Westfield, talked to national chains [to learn] what their demand is for space at malls, and we’ve also reviewed commercial transactions, public financings, SEC docs, tax rolls, planning departments, and the history of Sears and the history of the development of malls in the United States.”

After doing all that homework, Berkowitz said, “Every real estate expert we’ve hired cannot disprove our value.”

Neither Sears nor Fairholme Capital Management responded to a request for comment.

Sears stock dropped down 16 cents to $20.13 this morning but was essentially flat at mid-day trading.