Sandell Asset Management, an activist investment firm, has accumulated a large number of shares in Barnes & Noble Booksellers, and is urging the company to go private, CNBC’s Lauren Thomas reports.

Sandell, which the Wall Street Journal says is now among the book retailer’s top ten investors, believes Barnes & Noble’s $520 million market value is “unconscionably low,” the result of investors’ skittishness to buy into brick-and-mortar retail operations amidst the continued boom of the online marketplace.

On Tuesday, in a letter to the formerly iconic bookstore chain, Thomas Sandell, CEO of the Sandell firm, said investors’ wariness of retail is ill-advised. “Physical books, and physical bookstores, are not going away anytime soon,” the letter read.

“What makes the under-valuation of Barnes & Noble all the more shocking is that…there is but one truly national bookstore chain,” added Sandell. The letter also called the Barnes and Noble stores “beachfront property,” referencing, presumably, the desirability of the stores’ locations from a retail perspective.

The letter claimed Barnes & Noble, currently valued at $8 a share New York Stock Exchange, could sell itself for around $12 a share on the private market.

Public investors seem to support the move toward privatization. Since news of Sandell’s letter was released Tuesday, Barnes and Noble’s share price has jumped more than thirteen percent as of 12:15 Eastern, clearing the $8 dollar mark.

Barnes & Noble’s 1993 IPO gave it a market value of nearly $2 billion, according to CrunchBase.com. By early 2006, shares were worth almost 2.5 times their IPO value. But, in May 2007, the stock began to decline and has yet to recover. Since then, share prices have fallen more than 71%. Revenue has fallen almost 25% since 2013, according to eMarket retailer. 

Some of the falls can be attributed to the struggles of Barnes & Noble’s Nook, an eReader the company introduced to the market in November 2009 to compete with Amazon’s Kindle. Nook sales generated just $105.44 million in revenue in 2010, but Nook-based revenue spiked by over 550% in 2011, and rose another thirty-plus percent in 2012. Since then, though, Nook sales have been on the decline. Nook- based revenue fell more than 15% from 2012 to 2013, almost 35% from 2013 to 2014, and close to 50% from 2014 to 2015. In total, Nook revenue has fallen 85% since 2012 (data via statista.com).

In fiscal 2017, Nook-based sales dropped more than 23%, according to a June article by Ellen Duffer of Forbes Magazine.

“Digital just seems to be something that B&N can’t quite get right,” Duffer writes.

However, Sandell believes the company’s efforts to capture the digital market have been misguided. The true value of Barnes and Noble’s business, the letter implied, is its niche—not, mind you, its Nook—in the physical book market.

Barnes & Noble has flirted with private ownership before. Ronald Burkle began stockpiling shares in the company in 2008, building his stake to 20% by May of 2010. Amidst disagreements with the company’s management, many of which were over the emerging Nook business, Burkle launched an ultimately unsuccessful proxy war. In response, management instituted a “poison pill” measure preventing investors from compiling a stake larger than 20%.

Leonard Riggio, the retailer’s chairman and largest shareholder, who acquired the Barnes & Noble name and its flagship Manhattan store in the 1970s and was instrumental in building the company into the household name it is today, made a bid to buy back the operation’s retail arm in early 2013.  In the letter, Sandell suggests that Riggio once again endeavors to buy out the company.

Despite all the trendy talk about the demise of paper books, Sandell maintains that success can still be had in that market, and considers privatization Barnes and Noble’s first step toward reclaiming its past financial success.

“We are strong believers in the vital service that Barnes & Noble provides as the nation’s largest book retailer,” Sandell said in his letter.