Credit Suisse First Boston adopted a of recent origin equity research rating system in succession Sept. 9, and the ratings for three carriers - Continental Airlines (CAL), Delta Air Lines (DAL) and ExpressJet Holdings (XJT) - were lowered. The ratings for Continental and Delta dropp from purchase to Neutral and the rating for ExpressJet dropp from purchase to Under- perform. Yet in the case of Continental and Delta, the strange ...