What happened

Carnival (CCL 2.28%) stock hit a rock today after the cruise ship operator reported fiscal fourth-quarter 2018 results that beat Wall Street's expectations but just barely matched the Street's revenue forecast -- and included a warning on next year's earnings.

Earnings per share for the fiscal year's final quarter came in a penny ahead of analyst predictions of $0.70, pro forma. Sales were $4.46 billion.

Sharks circling a man standing in a canoe

Carnival's earnings warning attracts sellers. Image source: Getty Images.

So what

Carnival grew its Q4 revenue less than 5% year over year to $4.4 billion, marking a deceleration at the tail end of a year that has seen revenue rise nearly 8% (to $18.9 billion). The news on earnings was even worse: Carnival's GAAP profit of $0.71 per diluted share was a 7% decline year over year -- a stark contrast to overall fiscal 2018 results, which showed a 24% rebound in earnings per share.

Now what

Management characterized these results as "strong fourth quarter earnings," but investors may differ with that assessment. Carnival is forecasting that it will grow sales by 5.5% and pro forma earnings by about 9% in fiscal 2019, earning between $4.50 and $4.80. (Management did not give a GAAP forecast.) Taken at the midpoint, this guidance suggests likely earnings of about $4.65 per share, pro forma -- but Wall Street has been telling investors to expect $4.70 per share in 2019.

In essence, therefore, Carnival just piled an earnings warning atop a report in which the company only barely met expectations. That's reason enough for investors to be selling this morning.