Shares rose 8.3% to $14.96 this afternoon after CEO William Lynch vigorously argued at a Liberty Media investors’ meeting that stock buyers aren’t giving the book retail chain its due. With a market price of about $884M, the company that generated $7.2B in revenues last year “is undervalued,” he says. There’s a “strong, profitable and vibrant business” in its traditional bookstores, especially as rivals including Borders have closed. Lynch also urged investors to take a closer look at its new Nookmedia LLC partnership with Microsoft. The operation was valued at $1.7B this year when the computer giant invested $300M for a 17.6% stake in an operation that includes B&N’s Nook e-readers and tablets, e-Books, and college-targeted software. B&N’s stock price suggests that “investors are getting Nookmedia for free,” Lynch says. That overlooks the opportunities for the company as it builds its eBook sales, digital subscriptions, and eLearning — which he says has “big plans and announcements coming.”  Lynch also talked up the new Nook HD and Nook HD+ tablets, which have won encouraging reviews ahead of the October 25 ship date. Nookmedia is “a big and growing company in an exploding space,” Lynch says. Liberty owns 17% of B&N.