"As soon as it is possible to do so, several North American companies are likely to move quickly to enter Cuba, the greatest untapped opportunity remaining in the western hemisphere," says Jim Powell.

Here, the editor of Global Changes & Opportunities looks at what he believes are the best investment opportunities for investing in Cuba, should such a change occur.

"In August, Raul Castro announced that 500,000 public workers in Cuba will be laid off and will need to find jobs in newly-legalized small private enterprises.

The Dow Jones Industrial average jumped about 125 points on Monday but has given back about two-thirds of that gain through trading so far today. The story with the S&P 500 index is similar, though not quite so severe: a giveback of about a quarter of Monday's gain. The NASDAQ Composite index is doing better, up about 3% so far today, to remain virtually even with Monday's gains. The indices are slowly gaining back some ground lost earlier this morning, so by the close of trading today, the markets could show a small gain.

Here are the numbers:

Dow 9,712.28 -29.92 (-0.31%)
S&P 500 1,057.07 -3.54 (-0.33%)
Nasdaq 2,122.42 -1.62 (-0.08%)

In Pfizer's earnings preview post earlier this week, the largest drug company on the globe released earnings for its Q1 period this morning. Was it a doozy? Find out by looking at the results here, then follow the Pfizer Q1 conference call below as I liveblog it. Here's a teaser -- Q1 revenues were $12.4 billion with $4.8 billion in income. That's the way to do it, right?

Remember to use the "Refresh" button on your web browser to refresh your screen every few minutes -- updates will be happening very frequently. All times below are in EST:

12:00pm -- waiting for the Pfizer Q1 conference call to begin.

12:01pm -- the call starts right on time. Excellent. Pfizer's announcement starts with a moment of silence for the recent Virgina Tech victims. (silence)

12:02pm -- disclaimers are being read before we begin. The entire Pfizer executive team is on tap for this call apparently. Opening remarks are going on with some generalities from a script. Zithromax and Zoloft went off patent protection (denting revenues), but Pfizer pulled through on Lipitor and other drugs.

MOST NOTEWORTHY: Career Education Corp (CECO) and Expedia Inc (EXPE) were today's most notable downgrades:

• Prudential downgraded Career Education Corp (NASDAQ: CECO) to Underweight from Neutral with a $20 target based fourth quarter results and guidance.

• Expedia inc (NASDAQ: EXPE) was downgraded to Sector Performer from Sector Outperformer based on a deteriorating outlook and valuation following the weak fourth quarter.

OTHER DOWNGRADES:

• Various retail dining companies were downgraded today:
  
• Denny's Corp (NASDAQ: DENN) was reduced to Neutral from Buy at Merriman, citing weak traffic trends and the net unit growth delay into 2008.
• UBS downgraded Applebee's Int'l Inc (NASDAQ: APPB) to Neutral from Buy as they believe sales and traffic declines are likely to continue until easier comps in the second quarter.
  
• BB&T downgraded California Pizza Kitchen Inc (NASDAQ: CPKI) to Hold from Buy on valuation and concerns about earnings visibility.
  

• Constellation Brands Inc (NYSE: STZ) was cut to Neutral from Buy at Goldman Sachs on concerns around upcoming guidance and their belief that a recovery in the U.K. and Australia is at least a year away.
  

• Goldman downgraded WellCare Health Plans Inc (NYSE: WCG) to Sell from Neutral.
  

• Citigroup downgraded Petrobras Energia Participaciones ADS (NYSE: PZE) and Consolidated Communications Holdings Inc (NASDAQ: CNSL) to Sell from Hold.
  

• WedBush downgraded Take-Two Interactive Software (NASDAQ: TTWO) to Sell from Hold with a $15 target to reflect less optimism about the company's sport franchise and risk from the NY AG investigation.

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