BofA/Merrill analyst Andrew Didora says that with his BAC aggregated credit and debit card data showing robust growth in cruise spending and recent positive commentary from Royal Caribbean (RCL) and Norwegian Cruise Line (NCLH) on 2019 bookings, he is more constructive on 2019 net yield growth and is increasing his net yield estimates for both by about 100bps on average. The analyst continues to see the most upside in Norwegian Cruise Line shares and reiterates a Buy rating on the stock given the company's fleet flexibility, operating leverage, and valuation discount to Carnival (CCL) and Royal Caribbean.