There could be a battle of the billionaires brewing at Barnes & Noble, as companies controlled by investor Ron Burkle disclosed to the SEC that they have more than doubled their stake in the bookseller recently. Burkle’s companies now control 16.8 percent of the bookseller’s stock. That’s still only about half as much as the big block of stock controlled by chairman Len Riggio. Burkle’s recent purchases likely played a role in the recent upturn in BN’s stock, which lifted after reporting strong pre-orders for the nook. (Traders had been betting against BN, holding a lot of stock shorts that […]