Often tardy, but profitable

St. Pete-Clearwater International Airport had its busiest May in nine years, thanks to Allegiant Air, the industry's most profitable airline and reportedly its most tardy in 2012.

About 90% of the 83,595 passengers at St. Pete-Clearwater airport in May flew on low-cost Allegiant, a Las Vegas-based airline that flies to sunny places, such as Clearwater and Punta Gorda, from small cities.

The airline is a subsidiary of Allegiant Travel Co. (symbol: ALGT; recent price: $108.05), which has been profitable in 39 of the last 41 quarters.