Shares of Plexus ( PLXS) were among technology's losers Thursday, tumbling 29% after the electronics-manufacturing services company posted mixed third-quarter results and projected fourth-quarter results below Wall Street's forecast. For the period ended July 1, the company earned $25.1 million, or 53 cents a share, on revenue of $397.4 million. Results included a penny a share in stock-based compensation costs. Analysts polled by Thomson First Call expected earnings of 53 cents a share and higher revenue of $399.9 million. During the year-earlier period, Plexus reported a loss of $21.5 million, or 50 cents a share, on revenue of $313.7 million. The year-ago results included 66 cents a share in restructuring charges. Plexus sees fourth-quarter earnings of 46 cents to 50 cents a share, including about 3 cents a share in stock-based compensation costs and 2 cents a share in asset-retirement obligations. The company predicts revenue of $390 million to $405 million. Analysts project earnings of 56 cents a share on revenue of $418.3 million. Shares were trading down $9.83 to $23.77. Navteq ( NVT) sank 29% after the navigation-systems company posted weaker-than-expected second-quarter results. The company earned $23.8 million, or 25 cents a share, on revenue of $135.9 million. Analysts expected earnings of 28 cents a share on revenue of $142.4 million. During the year-earlier quarter, the company earned $25.3 million, or 27 cents a share, on revenue of $122.8 million. "We faced a number of challenges in the second quarter," Navteq said, "including unfavorable car sales trends and delays in customer product launches, which prevented us from achieving the results we expected." Shares were trading down $9.83 to $23.77. Shares of Silicon Image ( SIMG) jumped 15% after the chipmaker posted better-than-expected second-quarter results. The company earned $5.8 million, or 7 cents a share. Excluding items, the company earned $16.3 million, or 19 cents a share, beating Wall Street's target by 4 cents. Revenue totaled $70.6 million, compared with analysts' projection of $67.1 million. During the year-earlier period, the company posted adjusted earnings of $10.6 million, or 13 cents a share, on revenue of $50.7 million.