Storage vendor Adaptec ( ADPT) slashed guidance for its third and fourth quarters, citing weaker-than-expected sales at the reseller level. Pro forma to exclude certain costs, the company expects to lose 3 cents a share on revenue of $126.5 million in the December quarter. Analysts had been expecting earnings of 5 cents a share on revenue of $135.0 million, according to Thomson First Call. In the March quarter, Adaptec expects to break even or earn 1 cent a share, pro forma, on revenue of $127 million to $131 million. Analysts had been expecting earnings of 8 cents a share on revenue of $147.7 million. The stock tanked 92 cents, or 14%, to $5.54 on Instinet. The guidance reflects lower than expected channel sell-through, partially offset by higher demand among manufacturers who build with Adaptec products. "The lower channel revenue, coupled with a higher proportion of OEM revenue and greater start-up costs associated with new storage products, are expected to reduce gross margins and operating margins below the company's original expectations," the company said.