China Sunergy (CSUN), a Chinese company that makes solar cells from silicon wafers, sank 20.7% after swinging to a second-quarter loss. The company lost $3.8 million, or 14 cents per diluted share, vs. a profit of $1.6 million, or 9 cents a diluted share in the year-ago period. Analysts polled by Thomson Financial expected a profit of 2 cents a share. The company also announced that CFO Zhu Zhiping was resigning for personal reasons. Shares fell $1.54 to $5.91. The stock traded to a 52-week low.

Shares of Sonic Solutions (SNIC) plummeted 25% after Soleil downgraded the digital media software company to hold from buy. The stock closed down $2.60 to $7.80. The stock traded to a 52-week low.

BioFuel Energy Corp. said Friday Deloitte & Touche LLP resigned as the company's independent registered public accounting firm. BioFuel said the firm resigned as of Tuesday, according to a Securities and Exchange Commission filing. The company plans to find a replacement auditor in the next two weeks. The company said it had no dispute with Deloitte & Touche, and no significant disagreements on accounting matters related to financial statements for fiscal 2005 and 2006, as well as the interim period through Aug. 21 of this year. Deloitte & Touche had identified certain "material weaknesses" related to BioFuel's internal control over financial reporting, including a lack of adequate financial systems, lack of adequate accounting staff and lack of written policies and procedures. The company said it is continuing to address these issues. (AP) The stock traded to a 52-week low.

Trex (TWP) fell after saying Paul Fletcher has resigned as senior vice president and chief financial officer, effective Sept. 7. Fletcher is leaving to accept a position with a privately held technology company in the Washington, D.C., area. Shares of Trex, a Winchester, Va., maker of composite decking, railing and fencing, was down 5.3% at $13.34. The stock traded to a 52-week low.