Billionaire investor George Soros and David Neeleman, two men who helped launch No. 8 U.S. airline JetBlue Airways Corp., are selling portions of their holdings in the company, according to regulatory filings.

Soros reported in a U.S. Securities and Exchange Commission filing late on Monday that he had sold about 1 million shares of JetBlue, bringing his stake down to about 10.8 percent of the discount airline.

Soros' sale came the same week as Neeleman, the company's chairman, who sold almost one-quarter of his holdings in the company, according to a separate filing on Friday.

JetBlue removed Neeleman as chief executive from the company earlier in May.

"The recent sales by Soros and Chairman David Neeleman represent a strong bearish signal for JetBlue," said Ben Silverman, director of research at filing tracking site InsiderScore.com.

"Two long-term and committed shareholders taking money off the table with the stock down significantly from its January high and during a time of overall bearish sentiment towards the airline industry ... does not send investors a positive message."

JetBlue lost money for the first time in the fourth quarter of 2005 and has struggled since. In February, Neeleman and the company were criticized when an ice storm in New York brought JetBlue to a virtual standstill for several days.

JetBlue shares are off about 26.5 percent since January.

"When he (Neeleman) was CEO of our company he was very restricted by insider selling rules, so it was a personal, financial decision on his part, and he continues to have full faith in JetBlue," said Sebastian White, a JetBlue spokesman.

Soros, who once held as much as 33 percent of the company, had said in April that he owned 11.5 percent of the company.

"This fits the pattern," Silverman said. "He's been reducing his stake in the airline actually since 2003."

Soros still owns about 19.4 million JetBlue shares, according to the filing. Neeleman holds nearly 8.3 million shares, or about 4.6 percent of the company.

Neeleman made his name in the airline industry by starting a carrier called Morris Air and selling it to industry-beating discounter Southwest Airlines Co. Soros had provided some of the venture capital funding that helped Neeleman get the JetBlue flying in 2000.

JetBlue shares closed down 2.4 percent at $10.44 on the Nasdaq on Monday.