Editor's note: In this feature from Stockpickr, we highlight lists of stocks that have been upgraded by analysts or are experiencing activist investor situations or some other market-moving events.

Rumors of the Day: Recent rumors about the possibility of a WebMD ( WBMD) buyout were rekindled Thursday. StreetInsider.com reports that CNBC asked WebMD's CEO, Wayne Gattinella, about the rumors and he gave "no solid answer."
About a month ago, WebMD's stock jumped after Google ( GOOG) announced the departure of Adam Bosworth, head of its Google Health operation; this builds on the rumor that Google would prefer to acquire rather than build out a health site.
WebMD shares were sinking 3.4% to $59.25 in recent trading, while Google's were swinging higher and lower, recently down $1.89 at $623.50.

Today's Hot List: Target ( TGT) reported a 1.2% rise in September same-store sales, but the numbers were still lower than what the company and Wall Street expected. The retailer revised its full-year earnings to below $3.60 a share, which is in line with analyst consensus estimate. The stock dipped 54 cents to $65.23.

Also on the retail front, Wal-Mart ( WMT) reported that September same-store sales rose 1.4%. Wal-Mart, however, raised its earnings estimates -- from a previous range of 62 cents to 65 cents to a new range of 66 cents to 69 cents. The Wall Street consensus is 63 cents. The stock rose 3.4% to $47.13.

Analyst Downgrades: Wachovia downgraded Abbott Laboratories ( ABT) to market perform and also cut estimates. Wachovia believes the drugmaker is facing several challenges at its key franchises. Shares of Abbott fell 1% to $53.36.

Analyst Upgrades: JPMorgan upgraded Celestica ( CLS) from underweight to neutral. JPMorgan said downside appears to be limited and valuation at current levels is very attractive, as the stock is trading near tangible book value. The electronic instruments and controls company shot up 4% to $6.70.

Latest Activist Situations: StreetInsider.com 13D Tracker points to an amended regulatory filing on Denny's ( DENN), in which Olstein Capital Management disclosed a 9.5% stake, or roughly 8.9 million shares. Olstein said in the 13D filing that it believes shares of the restaurant chain are undervalued and that the company can take steps to increase the market valuation of the stock. The firm "plans to communicate with Denny's on alternatives for realizing the unrecognized value ... and suggestions for improving ... financial strength," according to the filing. Denny's shares lost 2.1% to $4.65.

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