Activist hedge fund Jana Partners declared in an SEC filing on Friday that as of April 11 they owned nearly 7 million shares of stock in Barnes & Noble, or roughly 11.7 percent of shares outstanding. The firm also holds a short-term bet of options to buy 250,000 shares at $13 share, exercisable May 18. The bookseller’s stock rose steadily during Monday trading on the news, gaining more than $2 a share (or 18.25 percent), closing at $13.41 a share, on heavy volume of almost 5 million shares. In early Tuesday trading, the stock had given back about 65 cents […]