You can add Obamacare exchange boss to this year's list of "most dangerous jobs."
Four out of the 15 chiefs of Obamacare insurance marketplaces run by individual states and the District of Columbia have either quit or gone on leave since the botched Oct. 1 launches of their health exchanges.
And given badly lagging sign-up rates in Affordable Care Act insurance policies in several other states, some other bosses likely will follow those four out the exit door.
"I would expect to see some more turnover, because they aren't hitting their enrollment targets," said Mark Argosh, managing principal Sterling Healthworks, a heath-care reform website featuring a calculator to determine premiums and cost, and a subsidiary of leading insurance brokerage SterlingRisk.
The latest casualty came Tuesday, when Minnesota's health exchange boss, April Todd-Malmlov, resigned during an emergency session of the board that oversees that exchange, called MNsure.
Todd-Malmlov had drawn heat for going on a two-week-long vacation to Costa Rica late last month, even after MNsure's website stumbled badly from myriad technical problems. Possibly as a result of those issues, Minnesota's enrollment levels have been mediocre, at best, with less than 5,000 people signed up for private Obamacare policies, according to most recently released data.
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"The recent problems some have encountered with MNSure are completely unacceptable," said Gov. Mark Dayton in a statement, after his assistant commissioner for Human Services, Scott Leitz, was named interim CEO of the exchange.
"I am hopeful that this new leadership will lead to their swift resolution," Dayton said.
Todd-Malmlov's departure followed the Dec. 6 resignation of the chief of Maryland's Health Benefit Exchange, Rebecca Pearce, after it was revealed that she had taken a long vacation in the Cayman Islands in late November as her Obamacare marketplace badly floundered, leaving it with just 5,179 people enrolled in private insurance plans by the date of her exit.
Maryland's exchange has performed so poorly that U.S. Rep. John Delaney, a Democrat who represents that state's Montgomery County, recently asked whether Maryland should abandon running its own Obamacare marketplace, and instead have residents sign up for such policies via the federally run HealthCare.gov.
Maryland Gov. Martin O'Malley's health commissioner in response said "we are considering all options," and The Baltimore Sun on Tuesday in an editorial said O'Malley administration officials "need to be" open to such options. On Tuesday, Maryland extended its deadline for enrolling in Obamacare policies that kick in on Jan. 1 from next Monday until Dec. 27.
Hawaii's Obamacare exchange chief Coral Andrews' resignation, which was announced in late November, became effective the same day as Pearce's departure from the Maryland exchange. As of Nov. 30, the Aloha State's troubled health exchange had enrolled just 444 people in private Obamacare plans, according to officials.
And on Dec. 1, Rocky King, the head of Oregon's Obamacare exchange, went on extended medical leave, with no guarantee that he would return, amid scathing criticisms of that marketplace. As of today, Oregon's exchange website has so many technical problems that it still hasn't been launched yet, and it's not known when it will be, leaving the state relying on paper applications and direct enrollment by insurers to fill the gap.
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As of Monday, Oregon officials said 7,597 people had selected private Obamacare plans, up from just 44 at the end of November.
The departures of the four state-run exchange bosses means that more than 25 percent of the chiefs of such exchanges have left their posts in less than three months.
And they came after President Barack Obama made a dramatic management move in late October by appointing Jeff Zients to oversee the frantic effort to repair the then-technologically crippled HealthCare.gov, the federally run marketplace that sells Obamacare insurance to residents of 36 states.
The appointment of Zients, who was replaced Wednesday by former Microsoft executive Kurt DelBene, was seen as a sharp rebuke to federal officials within the Health and Human Services Department who had repeatedly claimed over the summer that HealthCare.gov would be working as designed for its Oct. 1 launch.
Argosh, of Sterling Healthworks, said the fact that more than 25 percent of the state-run exchanges have lost their bosses so far "says the state exchanges have varied dramatically in terms of performance at this point."
Argosh noted that several other state-run exchanges including those in California, New York and Connecticut have performed much better, with fewer technological problems, and higher rates of enrollments.
"The state exchanges that are performing the best recruited experienced heads that had private-sector experience, and even public exchange experience," Argosh said.
(Read more: Long, long, long way to go to get to 7 million: Obamacare enrollment)
He also said that states hired different companies to build their own exchanges, which led to different degrees of success.
"It's not surprising that they're going to have a range of experiences," Argosh said.
Argosh said that going forward, states that have had problems with their Obamacare exchanges should be looking to hire executives with a combination of skills that can maximize the goal of getting a large number of uninsured people to sign up via a smoothly operating online interface.
"They need a combination of management talent, marketing talent and technology talent," he said.
—By CNBC's Dan Mangan. Follow him on Twitter @_DanMangan.