Carnival Corp topped second-quarter estimates yet shares are falling in Tuesday trading. The stock is gaining water after the cruiseliner company disappointed investors with its current quarter guidance. Over the three months to August, Carnival expects earnings between $1.38 and $1.44 a share, below analysts' estimates of $1.51 a share. That below-consensus guidance overshadowed bottom-line results exceeding estimates in its May-ended quarter. Over that period, the company earned 10 cents a share, 8 cents higher than expectations, while revenue of $3.63 dollars was over 4% year over year and beat forecasts.