Shares of Barnes & Noble (BKS -12.5%) get hammered in early trading after the firm misses consensus EPS estimates badly and says it expects full-year earnings to fall in the lower end of its previously issued guidance. The company says it will increase its spend on marketing and advertising for its Nook business - cutting into margins already razor-thin with rival Amazon (AMZN +2.2%) willing to sell e-readers at a loss (I, II).