My core investment strategy of trading strong penny stocks (which earned me 197% last year) has clearly benefited from the overall market's strength of the past few days. While I'm looking at these following five names, I'm not rushing into them just yet. Each has a different story to tell:

Ferro Corp. (NYSE: FOE), a struggling industrial materials maker whose stock price has plummeted in the past six months from the $20s to $1, basically doubled to $2 after the company amended its financing agreement -- meaning its lenders gave it some breathing room.

Analyst upgrades:

• Merriman upgraded shares of Akamai (NASDAQ:AKAM) to Buy from Neutral as they believe consensus expectations are now realistic and already reflect macro headwinds. Merriman also thinks the company's cost reductions could generate upside to EPS estimates.
  
• JP Morgan upgraded Novo Nordisk (NYSE:NVO) to Overweight from Neutral on expectations the company's diabetes drug will gain U.S. approval.
  
• Credit Suisse upgraded Pfizer (NYSE:PFE) to Outperform from Neutral and raised their target to $20 from $19 citing the merits of the Wyeth (WYE) deal and valuation.
• Quality Systems (NASDAQ:QSII) was upgraded to Buy from Neutral at Piper Jaffray.
  
• Parexel (NASDAQ:PRXL) was raised to Outperform from Market Perform at Wachovia.
  
• Ferro (NYSE:FOE) was upgraded at KeyBanc to Hold from Underweight.

• Reinsurance Group of America (NYSE: RGA) was upgraded to Buy from Neutral at UBS (NYSE:UBS) based on valuation.

• Ferro Corp (NYSE: FOE) was upgraded to Strong Buy from Sell at Matrix USA as the company's SEC filing status is now current; Matrix expects economic profitability to continue to improve.

• Oregon Steel Mills (NYSE: OS) was downgraded by UBS to Neutral from Buy; note that Evraz Group extended their cash offer to acquire Oregon Steel for $63.25 in cash.

• Gorman-Rupp (AMEX: GRC) and MGP Ingredients (NASDAQ: MGPI) were downgraded to Hold from Buy at Matrix USA, citing valuation for both companies.