Shares of Google ( GOOG) plunged $28.25, or 5.8%, to $458.19 after a report from research firm Comscore showed Web search-related paid clicks fell 0.3% in January compared with a year ago. In December, paid clicks grew 13% compared with a year ago. Analysts took the news as a sign that Google's growth, which largely comes from paid clicks, may be affected by the slowdown in the economy. UBS analyst Benjamin Schachter cut his 12-month price target on Google $590 from $650. CollaGenex ( CGPI) surged after Galderma Pharma agreed to buy the company for $420 million. Galderma will pay $16.60 a share, a 30% premium to the stock's Monday closing price. The deal is expected to close before the end of the second quarter. CollaGenex shares surged $3.53, or 28%, to $16.33. The stock was among the top movers of the Nasdaq biotechnology index, which was up 16.74, or 2.1%, to 806.83. Heading the opposite direction, Healthways ( HWAY) plummeted 34% after the health care programs company scaled back its estimates for 2008. The company now expects earnings of $1.50 to $1.55 a share, on revenue of $720 million to $740 million. Healthways had previously predicted a profit of $1.77 to $1.86 a share and revenue of $782 million to $815 million. The cut is due to slower-than-projected enrollment in a new health support program, the company said, based on issues with one large health plan customer and the expectation that two previously anticipated contracts will not materialize during this fiscal year. Friedman Billings lowered its price target for Healthways to $45 from $65 following the company's announcement. Shares fell $14.36 to $30.99. SanDisk ( SNDK) shares fell $1.35, or 5.1%, to $24.96, a day after its analyst meeting. Some analysts suggested that the price for NAND chips memory chips that SanDisk makes would continue to be weak this year even as competition from rival Micron Technology ( MU) is expected to intensify. Chattanooga, Tenn.-based Astec Industries ( ASTE), a maker of equipment and components for road building, utilities and construction, also rose on fourth-quarter numbers. Astec reported income of $11 million, or 50 cents a share, vs. $6 million, or 29 cents a share, in 2006. The Street had forecast EPS of 41 cents. Shares got a 17.1% bump up to $37.26. On the losing side, Cott ( COT) shares faded 38% to $2.51 after UBS downgraded the Toronto soft drink company to neutral from buy.