Calling all U.S. healthcare investors!

In case you missed it, the Supreme Court of the United States is expected to rule on the constitutionality of the Patient Protection and Affordable Care Act today. Signed into law by President Obama in 2010, the act, among other things, brings health insurance coverage to 30 million uninsured Americans.

There are a variety of decisions that can come down from the court today.

Here are the main actions to expect:

1) The court upholds the entire act

2) it overturns the entire act

3) it throws out the so-called Individual Mandate (which requires people obtain and pay for health insurance or else face a fine)

4) it also throws out the requirement for insurance companies to fund pre-existing conditions

5) the court overturns the Medicaid expansion requirement of the act.

6) A final possibility could be to put the whole thing off until 2014 because the courts can't actually rule until a fine has been levied!

The timing for the announcement is at 10 a.m. ET. Given the Act itself is more than 900 pages, one might anticipate the ruling to be more than a one page brief. Tuesday's ruling on Arizona's immigration law was discussed in a 76-page document. Often, however, the court does provide a syllabus, simultaneous with a decision's release that highlights the substance of the ruling.

Both sides of the Arizona immigration law claimed victory on Tuesday. Could something similar happen for this ruling? The court itself will likely be very clear. But since the outcome could include a variety of combinations, the first stock market reaction may be a wrong one.

For example, when the courts were hearing arguments back in March, there seemed to be a growing view that the individual mandate could be in jeopardy. Health insurers and HMOs rallied some 9% post the arguments. Hmmmm. Strange, because the individual mandate can substantially enhance the long haul revenues for the insurers (i.e. more insured, more fees). So the decision to throw out the individual mandate could actually hurt the stocks.

Another interesting thought is that "Obamacare" has been described as "nationalized medicine" by many of those who are against the law, and "free market" proponents could well believe that if the law is viewed unconstitutional it would be a good thing for companies involved in the industry. But what about all those newly insured Americans who might now be in a better position to use the services of hospitals and/or buy drugs to treat their diseases. That could be a good thing.

In any event, there will be more than one way to interpret the ruling. If you want to see how the market reacts to the news (both the first reaction and the sober-second thought reaction), here are a few ETFs to watch: iShares DJ U.S. Healthcare Providers (IHF-N) which includes the big HMOs and insurers; SPDR S&P Pharma ETF (XPH-N); SPDR S&P Healthcare ETF (XLV-N). I'd also be watching the U.S. bond market.

The ruling may be a major blow or support for the Obama administration and could have implications for the election in November and the fiscal position of the government (healthcare spending represents about 19% of U.S. GDP). For the bond market reaction, watch (TLT-N) --  iShares Barclays 20+ year treasury bond ETF.