While it didn't pass any legislation, President Obama's nationwide address on health care Wednesday night was a boon to some investors.

The prospects for reform remain uncertain, but investors signaled their own views Thursday by pushing up shares of Wellpoint (WLP), UnitedHealth Group (UNH) and Aetna (AET), the three largest managed care health-insurance providers. Managed-care stocks fell last spring on their decline in profitability and Obama's election. But each company has seen double-digit gains in the last three months as the prospects for a large government insurance program diminished. Obama s address Wednesday didn t change investor s sentiment.

Thursday's stock price moves in managed care show how deeply policy speculation has affected health-care companies, and demonstrate that the market believes that some form of health-care legislation will pass. While pharmaceutical manufacturers, medical device makers and clinical laboratories could also be affected, particularly under a plan championed by Senate Finance Committee Chairman Max Baucus (D., Mont.), the market's been most sensitive on managed-care names.

"Most of the recent fluctuations and variability we have seen daily moves of 2, 4, even 5% -- have been just on the changing tone of important people out of Washington," Morningstar analyst Matthew Coffina says. "All that volatility has been expanded by speculation around policy."

Whether Obama can exert his will on an increasingly fractious Congress won't be known until Baucus unveils a draft bill, now scheduled for review the week of Sept. 21. Prospects for the bill are far from certain, ISI Group policy analysts Tom Gallagher and Andy Laperriere wrote in a Thursday note.

"Last night President Obama gave a solid speech that we think will likely help his own poll numbers and boost public support for his health-care plan, at least temporarily," they wrote. "It should give the Democrats some momentum in the coming weeks, but we would caution that many of the contentious issues that Obama presented as settled or non-controversial remain tough legislative and political challenges."

But BMO Capital Markets analyst David Shove says the markets now back some kind of reform, and are voting with their wallets.

"The president spoke and the stocks went up," Shove says. "Normally, until recently, when the president has spoken, those stocks went down. Managed care and a lot of health-care names have been trading on [the belief that] reform wins." Coffina says reform talk has acted as a brake, and now that's being released. "Now, on fundamentals, the larger companies are pretty cheap, we think," he says.

Shove says the price-to-earnings multiples of several managed-care stocks could rise from their now-depressed levels once the health-care issue is settled in Congress "[Investors] will go back to the normal three questions: What's the price, what's the cost and how many members are you going to have?" he says.

While managed care pricing is alright, and insurers have adjusted to higher medical costs, the weak economy could soon assert itself on the industry. "Membership is horrible," Shove says. "Because Americans are not working. Also, investment income has dropped. It used to account for about 20% or more of revenue, now it's 10% or lower."

While political deal making continues and Wall Street takes a back seat to Washington, Coffina says investors still have a chance to profit from the health-care debate. "On a valuation basis, based on likely legislative outcomes, we think there's a significant enough margin of safety, especially for UnitedHealth and Wellpoint, that they're cheap enough -- relative to what's likely to happen -- that it's worth the risk."