It's because NSC had a better quarterly report than CSX. NSC beat the Street's projections while CSX fell short. Also, at the end of the quarter, NSC projected a much more optimistic outlook for their operations, while CSX projected same-o-same-o for the next quarter. I'm not sure, but I think that NSC also boosted their dividend payout while CSX stood pat on their dividends. JMHO.