NEW YORK (MainStreet) — Whatever millennials are doing with their money, it's not helping them much.

According to Moody's Analytics, millennials — the generation born between 1982 and 2004 — have a savings rate of negative 1.8% as of the second quarter of 2014, compared with 2.6% for Americans 35 to 44, and 5.7% for Americans 45 to 54.

That could be interpreted as millennials plowing all their assets into paying off debt. Moody's points out that average student loan debt stands at $17,200 for millennials, while their median net worth averages out to just $10,400.

But there's another interpretation: Millennials are simply spending rather than saving.

The ramifications are clear. With no money in the bank, millennials are highly vulnerable to job loss, illness or injury that keeps them from working and earning an income, or seeing their credit rating sink like a stone under all that debt.

Moody actually sees short-term gain, but long-term pain, in millennials' negative savings rates. "In the very near term it's a plus for spending and economic growth, but in the long run these households are not saving, and that will impair their ability to spend in the future," says Mark Zandi, chief economist for Moody's Analytics.

It puts millennials behind the curve in comparison with past generations, says Nicole Mayer, a financial adviser at Riverwoods, Ill.-based RPG Life Transition Specialists.

"The millennial generation is placing themselves in an increasingly vulnerable position," Mayer says. "The statistics show that young adults are paying for short-term gratifications rather than offsetting debts or contributing to a rainy-day fund."

Mayer says a stagnant savings pattern in a financial consumer's younger years will make it harder to navigate life obstacles such as job transitions or unexpected expenses, let alone retirement.

"Debts for the 35-and-under [segment] have increased, while net worth has decreased," she says. "One of the keys to having a healthy retirement account is contributing early so the funds have time to compound interest. Should this pattern continue, it could spell retirement trouble for millennials."

— By Brian O'Connell for MainStreet