President Obama offered a new health-care plan Monday, one that wants to do more to cap increases to insurance rates.

But even with this potential threat hanging over them, Humana (HUM), UnitedHealth (UNH) and other health insurance stocks were doing just fine Monday. Investors apparently don't think Obama's proposal will see the light of day, MarketWatch reports.

Adding fuel to the debate is a plan by one health insurer, WellPoint's (WLP) Anthem Blue Cross, to hike rates in California by as much as 39%. Obama is proposing to allow the Health and Human Services Secretary to block rate increases that are deemed unfair, according to The Washington Post.

So who determines whether a rate hike is fair? That would be up to a new board called the Health Insurance Rate Authority, according to the Post. The board would monitor premium increases nationwide and nip those that are too over-the-top.

Insurers that were heavily involved in Medicare were getting a boost Money from separate news. MarketWatch reports that a federal agency is planning a 1.4% increase next year to a payment rate for Medicare Advantage plans.

Here's how some of the insurers were doing in mid-day trading Monday:

Humana: Up nearly 5% to the $47 range. Humana has large Medicare plans, and investors were apparently cheered by the coming government payout increase.

UnitedHealth Group: Up nearly 3% and just shy of the $33 mark.

WellPoint: Even after being booed by the Obama administration, shares were up nearly 2% to pass $59.

The news wasn't as good for some pharmaceutical stocks, however. Obama wants to phase out the "doughnut hole," the Part D coverage gap in Medicare. To do that, he wants the pharmaceutical industry to pay $10 billion more in fees over 10 years, according to BusinessWeek.

Some of the largest pharmaceutical stocks were even or slightly down Monday. Johnson & Johnson (JNJ) was down by less than 1% while Bristol Myers Squibb (BMY) saw a drop of more than 1%. Pfizer (PFE) was about even.