Shares of Hornbeck Offshore Services ( HOS) were among the NYSE's losers Thursday, tumbling 20% after the oil service company cut its fourth-quarter earnings estimate. The company now projects earnings of 61 cents to 63 cents a share, down from an earlier forecast of 72 cents to 77 cents a share. The guidance includes a one-time gain of $1 million, or 4 cents a share. Analysts polled by Thomson First Call anticipated earnings of 75 cents a share. "On our last earnings call, we reported that market conditions for offshore supply vessels operating in the U.S. Gulf of Mexico were getting choppy," Hornbeck said. "However, during the latter half of the fourth quarter we experienced even more volatility than we expected." Shares were trading down $6.70 to $26.81. Six Flags ( SIX) climbed 10% after the amusement park operator agreed to sell seven of its amusement parks for $312 million. Six Flags will receive $275 million in cash and a note receivable for $37 million for three water parks and four theme parks. The sale of the parks will help Six Flags reduce debt and improve operational and financial flexibility, the company said. Shares were up 53 cents to $5.96. Shares of Lear ( LEA) jumped 10% after the auto parts seller forecast higher sales and profits in 2007. In a Securities and Exchange Commission filing, Lear forecast 2007 sales of about $15 billion, up from $14.5 billion in 2006 despite production cuts from U.S. automakers. The company sees operating earnings from its core businesses rising to $560 million to $600 million from $520 million to $550 million last year. Lear shares recently were adding $2.93 to $30.72.