The dealmaking is heating up in the nuclear sector. Today, Exelon Corp (NYSE: EXC) upped its hostile bid by 12% for NRG Energy (NYSE: NRG). This new price tag translates into a valuation of $7.45 billion.

The wrangling between the companies has gone on for roughly eight months. In fact, hostile deals can be time-consuming (in some cases, lasting a couple years).

Something else: Exelon has indicated that this is the "best and final offer." Apparently, the company has realized new cost savings, which justifies the higher valuation.

MOST NOTEWORTHY: UBS AG, Burger King and SAIC, Inc were today's noteworthy upgrades:

• Bear Stearns upgraded shares of UBS (NYSE:UBS) to Outperform from Peer Perform after UBS announced a $10B write-down and replenished capital, as they now believe the subprime issue is broadly behind the company and capital ratios are restored.
  
• Goldman raised its rating on Burger King (NYSE:BKC) to Buy from Neutral as they expect it to outperform the broader restaurant segment amid the current consumer weakness.
  
• SAIC, Inc (NYSE:SAI) was upgraded to Buy from Hold at Jefferies following the better-than-expected Q3 results, as they believe the company continues to outperform competitors and that margin expansion should continue.

OTHER UPGRADES:

• eBay (NASDAQ:EBAY) was added to Citigroup's CIR Recommend List.
  
• Banc of America upgraded Reliant Energy (NYSE:RRI) to Neutral from Sell.
  
• MasterCard (NYSE:MA) was upgraded to Outperform from Market Perform at Keefe Bruyette.

MOST NOTEWORTHY: Palm, Inc (PALM), Reliant Energy, Inc (RRI) and Take-Two Interactive Software (TTWO) topped today's more notable downgrades:

• UBS cut Palm, Inc (NASDAQ: PALM) to Reduce from Neutral citing valuation. Bank of America downgraded shares to Neutral from Buy with an $18 target and considers the risk/reward less favorable at these levels.

• Bank of America also downgraded Reliant Energy (NYSE: RRI) to Sell from Neutral on valuation.

• Hillard Lyons cut Take-Two Interactive Software (NASDAQ: TTWO) to Neutral from Outperform.

OTHER DOWNGRADES:

• CIBC downgraded Jabil Circuit, Inc (NYSE: JBL) to Sector Performer from Outperformer following the company's disappointing outlook. Bear Stearns cut Jabil to Peer Perform from Outperform. BMO cut the company to Market Perform from Outperform.

• Friedman, Billings, Ramsey downgraded shares of FormFactor, Inc (NASDAQ: FORM) to Market Perform from Outperform to reflect increased risks in the logic market and long-term growth concerns.

• Matrix USA downgraded Knight Transportation (NYSE: KNX) to Hold from Buy.

• American Technology downgraded shares of Comverse Technology, Inc (NASDAQ: CMVT) to Neutral from Buy as the firm believes a retreat to the $17 range is likely given the company's disappointing margin trends.

• CL King cut Claire's Stores, Inc (NYSE: CLE) to Neutral from Strong Buy following the buyout offer.

• Goldman downgraded Atmos Energy Corp (NYSE: ATO) to Sell from Neutral and Liz Claiborne, Inc (NYSE: LIZ) to Neutral from Buy.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).