(Bloomberg) -- Steady improvements in American life expectancy have stalled, and moreAmericans are dying at younger ages. But for companiesstraining under the burden of their pension obligations, thedistressing trend could have a grim upside: Ifpeople don’t end up living as long as they were projectedto just a few years ago, their employers ultimately won’t haveto pay them as much in pension and other lifelong retirementbenefits.

In 2015, the American death rate—the age-adjusted share ofAmericans dying—rose slightly for the first time since1999. And over the last two years, at least 12 large companies,from Verizon to General Motors, have said recent slips inmortality improvement have led them to reduce their estimates forhow much they could owe retirees by upward of a combined $9.7billion, according to a Bloomberg analysis of company filings.“Revised assumptions indicating a shortened longevity,” forinstance, led Lockheed Martin to adjust its estimated retirementobligations downward by a total of about $1.6 billion for 2015and 2016, it said in its most recent annual report.

Mortality trends are only a small piece of the calculationcompanies make when estimating what they’ll owe retirees, andindeed, other factors actually led Lockheed’s pension obligationsto rise last year. Variables such as asset returns, salary levels,and health care costs can cause big swings in what companies expectto pay retirees. The fact that people are dying slightly youngerwon't cure corporate America’s pension woes—but the fact thatcompanies are taking it into account shows just how seriousthe shift in America’s mortality trends is.