(Reuters) - Shares of U.S. cruise operators, including Norwegian Cruise Line Holdings, surged in midday trading on Wednesday as brokerage Citi gets bullish on the companies' long-term prospects.

Shares of Norwegian Cruise were up as much as 11% following an upgrade from Citi to "buy" from "neutral," while Royal Caribbean Group's shares reached an all-time high of $263 after rising as much as 5%. Carnival Corp surged nearly 9%.

Cruise operators have posted strong results this year, riding on solid appetite for sea-based vacations and higher ticket prices. Americans have splurged on experiences and services over discretionary goods, resulting in record booking rates for affordable cruise voyages.

September cruise traffic was among the best on record, while pricing data remains consistently positive when looking to 2025 and beyond, Citi said, based on web traffic analysis.

"Norwegian's shift in strategy from quality at all costs to a more balanced yield/cost relationship gives us confidence that the considerable pricing power and the company's increased focus on costs 'can't help but bear fruit'," Citi analyst James Hardiman said.

The brokerage raised price targets on Norwegian Cruise to $30 from $20, Royal Caribbean to $253 from $204 and Carnival by $3 to $28.

Both Royal Caribbean and Norwegian Cruise are expected to grow capacity at a healthy 6% annual clip over the next three years, Citi said, adding that it would be the biggest contributor to their revenue growth.

So far this year, stocks of Royal Caribbean, Norwegian Cruise and Carnival are up 50%, 14% and 9%, respectively, including session's moves.

Norwegian Cruise's forward price-to-earnings ratio for the next 12 months, a common benchmark for valuing stocks, was 11.05, compared with 13.99 for Royal Caribbean and 11.31 for Carnival.

(Reporting by Savyata Mishra and Neil J Kanatt in Bengaluru; Editing by Alan Barona)