The realities of annuities are being revealed to both buyers and sellers as interest rates in the United States creep along near 0%. Sellers are finding it harder to live up to promises of guaranteed return rates, and buyers are finding it harder to believe them.

As the Wall Street Journalโ€™s Hester Plumridge writes, on Wednesday, ING Group โ€œbooked a โ‚ฌ1 billion ($1.34 billion) charge to cover higher-than-expected liabilities on U.S. variable annuities.โ€ Insurance companies have made a fortune selling annuities to unwary investors looking for what were described as โ€œguaranteedโ€ returns. As a result, today variable annuities account for $1.6 trillion worth of assets in the U.S. retirement product market.

INGโ€™s increased liabilities estimates may not be high enough. Plumridge writes โ€œING says it has only just got enough data on policyholders’ behavior to start predicting their actions. Topping up reserves to an adequate level could cost ING a further โ‚ฌ3 billion, estimates J.P. Morgan Chase. The uncertainty could complicate ING’s efforts to divest its U.S. insurance business by 2013.โ€

Plumridge explains that ING is not alone, and โ€œPeers may be able to temporarily mask shortfalls with surpluses from other business lines. Insurers including MetLife, Prudential Financial and Prudential PLC all have large variable-annuity books that could be affected by changing behavior among policyholders.โ€

Since the Federal Reserve lowered rates as far as they possibly could, savers and retirees have had their wealth threatened. Those who purchased annuities received โ€œguaranteedโ€ returns, but those guarantees may outlast some of the insurers who gave them.