Shares of WCI Communities ( WCI) were among the NYSE's winners Tuesday, jumping 10% after financier Carl Icahn disclosed that he boosted his stake in the homebuilder. According to a Securities and Exchange Commission filing, Icahn and his affiliates now own about 14.6% of WCI's stock. The filing said that the buyers acquired the shares because they believe them to be undervalued. Icahn also plans to contact the company to discuss the business and how to unlock value on the shares, the filing indicated. Shares of WCI recently were trading up $2.10 to $23.12. TD Ameritrade ( AMTD) climbed 5% after the online brokerage firm posted better-than-expected first-quarter results. The company earned $145.6 million, or 24 cents a share, for the December quarter. Excluding items, earnings were $173 million, or 28 cents a share. Analysts polled by Thomson First Call expected earnings of 22 cents a share, before items. Ameritrade's revenue totaled $535.2 million, topping Wall Street's estimate of $517.4 million. During the year-earlier quarter, the company earned $86 million, or 21 cents a share, on revenue of $277.3 million. For 2007, TD Ameritrade projects earnings of $1.10 a share. Analysts predict earnings of $1.12 a share. Shares were adding $1 to $18.35. Shares of Tidewater ( TDW) rose 1% after the provider of offshore supply vessels predicted that third-quarter earnings will top Wall Street's expectation. For the quarter ended Dec. 31, the company estimates earnings of $1.61 to $1.68 a share, including a one-time gain of 7 cents a share. Analysts, on average, project earnings of $1.45 a share. Shares were trading up 59 cents to $46.12.