The players may be largely the same, but the business of life reinsurance looks very different than property/casualty reinsurance.

Perhaps the biggest difference is the nature of the reinsurer's commitment, experts say. Whereas a property/casualty reinsurance treaty may last only a year, a life reinsurance contract could last decades.

The nature of the risk varies considerably, too. Life reinsurance involves human mortality, which can be easier to underwrite. Property/casualty reinsurance involves more unknowns, where a single hurricane can have a major effect throughout the market.

Where the two industries bear some resemblance is in the identity of the major underwriters, said Bill Pargeans, assistant vice president in the life/health rating division of A.M. Best Co. Inc. in Oldwick, New Jersey.

In North America, the five largest life underwriters are Swiss Re Life & Health Inc., Munich American Reassurance Co., Scor Global Life Americas, Reinsurance Group of America Inc. and Hannover Life Reassurance Co. of America, he said.

Of those five, only St. Louis-based Reinsurance Group of America is not involved in the property/casualty reinsurance arena, he said.

“Once you get past that, market share really drops off,” he said.

According to a survey earlier this year by Munich Re on behalf of the Schaumburg, Illinois-based Society of Actuaries, the five underwriters accounted for 93% of the U.S. life reinsurance market.

Ferris Joanis, an associate director at Standard & Poor's Rating Services in New York, said for property/casualty reinsurers, the life insurance business “adds a certain measure of stability.”

“To some degree, life reinsurance is a bit easier to underwrite,” than property/casualty risk, Mr. Joanis said. “It's a well-understood risk class” and “risk is spread out globally — there's not a huge concentration of risk.”

Mr. Joanis also pointed out there has been a considerable amount of merger and acquisition activity in recent years in the life reinsurance market. For example, the Munich Re survey said that Scor acquired Generali US Life Re Generali U.S. Holdings Inc. in October 2013, increasing its 2013 U.S. market share to 28.2% from 17.2% a year earlier.

Neil Sprackling, Swiss Re head of life and health for North America in Armonk, New York, said life reinsurance is not experiencing the flood of hedge fund and private equity players that have entered the property/casualty reinsurance market.

“A lot of entrants on the P/C side are coming with a view to making some short-term gains,” Mr. Sprackling said. But new players in the life reinsurance market would tie up capital possibly for decades. “Once you sign up to deal, you're in,” he said.

Mike Taht, senior vice president of life reinsurance at Munich American Reassurance in Atlanta, also stressed that the life reinsurance contract is a long-term deal.

“Therefore, the life reinsurance contract is one where we're on the risk for the life of the policy,” Mr. Taht said.

“The property/casualty market has a pretty well-defined pricing cycle, whereas that type of cyclical nature of the life reinsurance market is not really there,” he said. “We're on a long-term contract. Experience emerges over time.”

The risk concentration in the two reinsurance sectors is different, said Howard Mills, director and chief adviser in the insurance industry group at Deloitte L.L.P. in New York.

On the property/casualty side, risk concentration is a “huge issue — one single storm can bankrupt a property/casualty insurer or reinsurer,” he said. On the life side, concentration is much smaller, and the risks are long-tail.

Payouts are predictable, too. If someone buys an individual life policy with a $1 million value, that person's beneficiaries will get $1 million, Mr. Mills said. On the property/casualty side, the payout is unknown until the event triggering damage has occurred.

But a pandemic could wreak havoc with the life side risk concentration for both life insurers and reinsurers, Mr. Mills said.

Overreliance on antibiotics could lead to the emergence of antibiotic-resistant strains of inflection and “that could be a game changer,” he said.

Changes in longevity have affected the life reinsurance business, said Joe Gilmour, CEO of Scor Global Life Americas in Charlotte, North Carolina.

“To be competitive in pricing, you have to assume something about future mortality,” he said. “If it's better, you have upside; and if it's not, you have downside in what you put in your original pricing.”

The market itself is “highly competitive,” Swiss Re's Mr. Sprackling said. That's due in part to a “trend for close to a decade of life insurers to hold more of the risk on their own balance sheet.” He said the cession rate from primary insurers has dropped in recent years, albeit from “all-time highs that were not sustainable.”

The Munich Re survey results support that. The life reinsured rate in 2001 was 59.2%, which dropped to 27.2% by 2013, according to the survey.

Despite the drop, Mr. Sprackling said “we're cautiously optimistic about the future.”

“The life insurance business is certainly important to our clients,” Scor's Mr. Gilmour said. He said traditional life insurance became less attractive to primary life insurers for a while because annuities appeared more attractive.

“Now a lot of clients are moving back to protection,” he said. “There's more spending on doing more life insurance sales.” Nevertheless, “some of our clients effectively become our biggest competitors because they keep more of the risk if they like it.”

Still, “I'm quite bullish on where life reinsurance goes,” Mr. Gilmour said.