Editor's Note: In this feature from Stockpickr, we highlight lists of stocks that have been upgraded by analysts, are experiencing activist situations or some other market moving events.Rumors of the Day: Credit-battered Bear Stearns ( BSC) was jumping 11% on renewed speculation about a large investment from a European or Chinese bank, according to the Associated Press. The New York Times also reported superinvestor Warren Buffett was considering a 20% stake. Bear declined to comment. The stock jumped $12.51 at $126.75. Highland Capital Management, which owns 4.7% of PDL BioPharma ( PDLI), in a letter urged the company to explore a sale and called for Chairman Patrick Gage and CEO Mark McDade to step down immediately. Dan Loeb's Third Point, another large PDL BioPharma investor, has also called for a sale and resignations of the two executives. McDade in August said he planned to step down by the end of the year. Shares added 25 cents to $21.05. Today's Hot List: Chevron ( CVX) announced a $15 billion buyback program, to be executed over the next three years. The new program follows three buybacks of $5 billion each that were completed in 2005, 2006 and September 2007. The company added 75 cents at $92.63. General Motors ( GM) and the autoworkers union have reached a tentative agreement on a new national labor contract. The pact includes the framework for an independent retiree health care trust, as well as other changes to the national agreement. GM spiked $3.39, or 9.9%, to $37.81. Analyst Downgrades: Merrill Lynch downgraded electronic manufacturing services provider Jabil Circuit ( JBL) to sell. The firm said the stock could fall 20% from current levels. Shares slumped 77 cents, or 3.1%, to $24.43. Analyst Upgrades: Wachovia upgraded youth retailer American Eagle ( AEO) to outperform from market outperform. The bank said the company is well positioned for the end of the year and raised its estimates. Shares gained $1.44 to $26.41. Latest Activist Situations: In an amended regulatory filing on marine and heavy-duty transmission component maker Twin Disc ( TWIN), investor Clarus Capital said a recent press release from the company was "highly misleading" and said the firm is interested in its 5.1% holder investment beyond the short-term. Clarus reiterated its call for Twin Disc to hire an investment bank to explore a sale of the company, saying there are parties who are interested in paying a significant premium to its current price. The stock increased $1.73 to $58.20.