Updated from 4:11 p.m.Qualcomm ( QCOM) dropped 6% late Wednesday after the communications-chip company offered weak fourth-quarter revenue guidance. For its fiscal third quarter ended June 25, the San Diego wireless-tech shop made $643 million, or 37 cents a share, up from the year-ago $560 million, or 33 cents a share. Revenue rose to $1.95 billion from $1.36 billion a year earlier. On a pro forma basis, excluding certain costs, earnings were 42 cents a share. Analysts surveyed by Thomson Financial were looking for a 42-cent profit on revenue of $1.95 billion. But Qualcomm also said Wednesday that fiscal fourth-quarter revenue would be about $1.94 billion, shy of the $1.98 billion Thomson Financial forecast. Shares fell as much as 11% in early postclose action before recovering to be down around 6%. Last month, Qualcomm boosted its fiscal third-quarter guidance, citing strong consumer demand for third-generation wireless services like Web browsing and email. Qualcomm boosted its handset sales and per-unit pricing estimates at that point. Qualcomm, down 14% this year heading into the postclose report, fell 67 cents in regular action before dropping $2.24 late Wednesday to $34.49.