Shares of Sigmatel ( SGTL) slid 11% after the chipmaker cut its fourth-quarter sales estimates and announced the resignation of its chief executive. The company projected fourth-quarter revenue of $37 million to $38 million, below its October forecast of $41 million to $46 million. Analysts targeted revenue of $43.8 million. Sigmatel said that Chairman, President and CEO Ronald Edgerton resigned to "spend more time with his family." The company named board member William Osborne chairman. Phillip Pompa, the senior vice president of the company's portable systems group, will become interim CEO. Shares of Sigmatel were down 51 cents to $3.99. Other heavily traded tech stocks Thursday included Intel ( INTC), up 78 cents to $21.13; Cisco ( CSCO), up 44 cents to $28.17; Sun Microsystems ( SUNW), up 10 cents to $5.64; Microsoft ( MSFT), down 1 cent to $29.85; Sirius Satellite Radio ( SIRI), up 2 cents to $3.76; Level 3 Communications ( LVLT), down 7 cents to $5.58; Apple Computer ( AAPL), up $1.47 to $85.27; and EMC ( EMC), up 25 cents to $13.45.