The book retail chain’s shares are up 8.1% in mid-afternoon trading, making it one of the day’s biggest gainers in the media pack. Barron’s appears to be largely responsible for the move after it seized this weekend on reports that Microsoft might be willing to pay $1B for Barnes & Noble‘s NOOK tablet and e-reader platform. “It’s possible Microsoft may bid for Nook or the whole company, and there could also be interest from Liberty [Media]” which already owns 17% of Barnes & Noble, Barron’s says. Deals could send shares up as much as 50% the magazine estimates. The Microsoft rumor took off two weeks ago after Techcrunch cited “internal documents” that confirmed an offer. That sent shares to a 52-week high of $23.71. But enthusiasm fizzled last week when website Insider Monkey reported that a “highly placed source inside Microsoft” said an acquisition “is not happening in the foreseeable future.” That hasn’t put speculation about a big deal to rest. Founder Leonard Riggio has said that he might make an offer for the retail stores, although he hasn’t made it yet. Meanwhile Techcrunch yesterday cited “a source close to the matter” who says that Barnes & Noble is preparing to add a web browser, email, and apps to the Nook Simple Touch e-readers — potentially a big boost in functionality for a $79 device. The company recently added Google Play apps and services to its NOOK tablets.