Investors and analysts are convinced that insurers are set to join the wave of consolidation taking place in the health-care sector, though it's still uncertain how the acquisition pairings could play out among the top insurers.
"We believe Aetna could be a strategic buyer of Cigna," wrote Leerink Partners analyst Ana Gupte in a note to clients. She added that potential deal "may play out more favorably from a timing and CEO succession perspective given the two leaders at the helm."
For regulators, the big question is whether consolidation among the major insurers would reduce competition. Part of the goal of the Obamacare legislation was to create a competitive individual consumer insurance market.
But consumers, have other questions, namely, what does this mean for their wallets.
The good news is policy experts aren't sure insurer consolidation would result in higher prices in the consumer market.
"The Affordable Care Act certainly can be seen as driving consolidation on the provider side," resulting in hospitals becoming bigger over the last five years, said Timothy Jost, a professor at Washington and Lee University School of Law.
"It may be that the insurers would see the need to consolidate in the face of provider consolidation," he said.
Katherine Hempstead, a director at the Robert Wood Johnson Foundation, pointed to studies in the last few years that back up the notion that provider rather than insurer concentration plays a bigger role in consumer markets.
"The research is pretty unequivocal … that the impact on prices seems to be much more affected by consolidation by providers, and that when payers consolidate there tends to be much less impact in terms of higher prices for consumers," Hempstead said.
An analysis of hospital consolidation in the Journal of American Medical Association in 2013 concluded that while larger systems provide advantages for more efficient health care, more often than not hospital mergers resulted in price increases of 10 percent to 40 percent. The provider concentration also made it more difficult for insurers to gain better pricing.
"Some people say when insurers have more market power then they actually can negotiate better deals with providers," said Hempstead.
"That's the sumo wrestling theory—that you put two big-bellied bodies in the middle and you'll be better off," said Tim Greaney, a professor and co-director at the Center for Health Law Studies at Saint Louis University School of Law.
Beyond the individual market, Greaney worries that a more concentrated market of large insurers will reduce competition in the employer market.
"To the extent that they're not as competitive, that just sort of raises the costs to employers," he said. "So, potentially, you could have a pretty broad-reaching effect."
The speculation over insurer dealmaking comes as the U.S. Supreme Court is set to issue a ruling as early as Thursday in the King v. Burwell case on the matter of Obamacare federal exchange subsidies.
If the justices rule that subsidies are illegal in the 34 states using the federal exchange, close to 6.4 million Americans would lose access to the tax credits that make their insurance more affordable, and that could throw the individual insurance market into turmoil.
Despite that, analysts said they don't think a ruling in favor of King would derail merger activity.
"I wouldn't expect it to have any material impact," said Chris Rigg a health analyst at Susquehanna Financial Group. "Seems like the process is too far along."
Although the Obamacare marketplaces are growing, they are not yet as important to insurer profits as the Medicare and Medicaid government business, which would not be disrupted if the court rules against subsidies on HealthCare.gov.
"Cigna has no exchange business to speak of, so should not matter," said Leerink's Gupte. "Humana is losing money on federal exchange, so it would actually be a positive for an acquirer."
"There's so much spaghetti being thrown against the wall it's hard to predict what's going to emerge," said Professor Greaney. "I think a safe bet for any executive is 'let's just get bigger, it will be harder to push us around.'"