Sales of indexed annuities surged 23 percent last year, prompting banks including JPMorgan Chase & Co. to expand into the booming structured-product market.

Symetra Financial Corp. began marketing annuities whose returns are derived from JPMorgan’s ETF Efficiente 5 Index on Tuesday, according to Diana McSweeney, a Symetra spokeswoman.

The index, which targets a low volatility level by rebalancing monthly between cash and 12 exchange-traded funds that track a variety of assets from gold to high-yield bonds, is already used in structured notes and market-linked CDs.

The New York-based lender joins banks including Barclays Plc and Goldman Sachs Group Inc., who have partnered with companies in the indexed-annuity market, where sales reached a record $48.2 billion in 2014, according to data released by the Limra Secure Retirement Institute last week. That’s a $9 billion increase from the prior year, in part due to the rise of specialized indexes.

Many indexed annuities are “offering an uncapped feature, which is obviously a nice selling point,” said Todd Geising, senior business analyst for the annuity market at Limra. About a dozen specialized indexes were introduced in 2014, he said.

In the third quarter, 27.7 percent of indexed-annuity sales were tied to such so-called hybrid indexes, according to Wink’s Sales & Market Report. That’s helped reshape the indexed-annuity market, which has traditionally offered products whose returns are based on benchmarks like the Standard & Poor’s 500 Index.

Inflated Expectations

It’s also attracted the attention of Iowa Commissioner of Insurance Nick Gerhart, who suggested that some marketing materials may inflate investor expectations by offering uncapped rates of return even though the design of underlying indexes may limit returns.

For some companies, strong sales of indexed annuities have already helped boost earnings. Allianz SE said in an investor presentation on Feb. 26 that a product tracking the Barclays U.S. Dynamic Balance Index helped its indexed annuities business to more than double in 2014 to $12.8 billion.

Western & Southern Financial Group Inc., which introduced an annuity tied to a Goldman Sachs index in September, says the product has grown faster than any of its other annuities, according to Mark Caner, president of W&S Financial Group Distributors Inc., a division of Western & Southern Financial Group.