US Airline stocks took their biggest plunge in 11 weeks on Wednesday on what an analyst said were valuation concerns after a rally which bolstered the sector by 40 percent from a two-year low in September.

US Airways Group, whose shares had nearly doubled since its listing on the New York Stock Exchange in September, led the rout, and were down USD$2.85, or 7.54 percent, at USD$34.95.

Discount carrier Frontier Airlines was 54 cents, or 6.38 percent lower at USD$7.93, and Continental Airlines was down USD$1.28, or 5.96 percent, at USD$20.21. The sectoral Amex Airline index was down 3.9 percent, its biggest percentage decline since October 20.

"It's a market adjustment," said Ray Neidl, an analyst at Calyon Securities. "This market from early January is just way overvalued."

He added that persistently high fuel prices were also a problem.

"I just don't think this industry can make money with oil above USD$50 a barrel," he said.

US crude oil futures ended up but off highs on Wednesday, at USD$64 a barrel and jet fuel is selling for about USD$7 more than that.