Investors frequently like to chase "hot stocks." While not based on fundamentals, momentum investing does sometimes work as stocks that are "working today" frequently "work tomorrow" as well.

So, as 2008 is 1/6th done, it's time to look back at the highfliers from 2007 and see where they're trading today. As usual, the analysts at Bespoke Investment Group have some good data and charts for us.

In a post, titled "How the Best Have Done," Bespoke analyzes the best performing U.S. stocks of 2007 and tracks them into 2008. The results:

• First Solar Inc. (NASDAQ: FSLR), 2007's best performer, is down 21.86% year to date. See BloggingStock's Aaron Katsman's article on why he shorted this stock into the New Year.
  
• The second best, Onyx Pharma Inc. (NASDAQ: ONXX), is down 49.51%.

While some solar stocks are down big in 2008 after a huge run-up in 2007, the big winners are heavily concentrated in materials, agriculture, and energy. BPZ Resources Inc. (AMEX: BZP) is the stock on the list that has done the best in 2008 -- rising another 44% so far this year.

Zack Miller is the managing editor of IsraelNewsletter.com and a former equity analyst for a leading multinational hedge fund.

Onyx Pharma (NASDAQ: ONXX) is recently is down $9.23 to $35.70 in pre-open trading.

ONXX and its partner Bayer halted Phase 3 trials of Nexavar and after the company reported a larger than expected Q4 loss.

ONXX overall option implied volatility of 63 is above its 26-week average of 57 according to Track Data, suggesting larger price movement.

Option Update is provided by Stock Specialist Paul Foster of theflyonthewall.com

MOST NOTEWORTHY: Nokia (NOK) and Pfizer (PFE) topped today's list of downgrades.

• Prudential downgraded Nokia Corporation (NYSE:NOK) to Neutral from Overweight to reflect what they believe will be a slowing of the handset market in 2007, as well as the company's pending legal battle with Qualcomm (NASDAQ:QCOM).
• Following the unexpected halt of Torcetrapib, Pfizer Inc. (NYSE:PFE) was downgraded by a multitude of companies: At Lehman, to Underweight from Overweight; at JP Morgan, to Neural from Overweight; at Merrill Lynch, to Neutral from Buy; and at Morgan Stanley, to Equal Weight from Overweight.

OTHER DOWNGRADES:

• Onyx Pharmaceuticals Inc. (NASDAQ:ONXX) was downgraded to Neutral from Overweight at Prudential following the failure of their Phase III melanoma trial.
• Alcatel-Lucent (NYSE:ALU) was downgraded to Sector Perform from Outperform at RBC Capital Markets; the firm expects limited near-term revenue momentum from integration risks and internal/external uncertainties.
• ThinkEquity downgraded Novellus Systems Inc. (NASDAQ:NVLS) to Accumulate from Buy, as they believe Novellus is no longer deeply undervalued and only expects a gradual margin expansion from here.

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