By Anne Tergesen

BlackRock Inc. /quotes/zigman/249424/delayed /quotes/nls/blk BLK. a huge money-management firm that has been trying to capture a bigger share of the retiree-savings market, is rolling out a suite of mutual funds that aim to generate long-term investment returns that keep pace with the income offered by immediate annuities.

Shutterstock.com Income without an annuity lockdown.

The so-called CoRI funds, which will invest mainly in Treasury and high-quality corporate bonds, will enable investors to purchase a specific amount of inflation-adjusted lifetime income from age 65 on. For example, a 55-year-old man who thinks he will need $35,000 a year starting at age 65 can ensure today that he will get it for an up-front investment in a CoRI fund of $462,000. At the same time, his principal won’t be tied down or subject to early-withdrawal penalties, the way it might be if he bought an actual annuity.

The returns of the funds will track indexes that are designed to forecast the future price of immediate annuities. (The first set of funds will track annuity purchase prices in 2015, 2017, 2019, 2021, and 2023.)

Investors can find out how much income their nest egg will produce if invested in one of the new products by using this calculator. (For more on how the calculator works, see this recent piece in The Wall Street Journal .)

Of course, there is no guarantee the funds will perfectly track immediate annuity prices. Perhaps the biggest threat is an unexpected rise in inflation, says Chip Castille, head of BlackRock’s U.S. Retirement Group.

But in return for a bit of uncertainty, investors can keep their money liquid until they decide whether to purchase an immediate annuity. Those who keep their money in the funds will receive dividends – the funds will pay them annually starting at their maturity date. Ten years after the maturity date, the funds will be liquidated and the balance returned to investors.

The 10-year waiting period is designed to give the typical investor until his or her 70s to make a decision about an annuity purchase, says Castille. At that point, “many people get clarity around their health and spending needs. It’s a good time to make a decision,” he adds.

The new BlackRock funds—which will debut this spring—will invest mainly in Treasury bonds and high quality corporate bonds, says Castille. A BlackRock press release says the funds can also invest in “other financial instruments.”

Starting this summer, the firm aims to offer the CoRI funds in its LifePath series of Target Date funds, which are available in some 401(k) plans. Fees for the funds hadn’t been determined as of press time.

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Anne Tergesen covers retirement for The Wall Street Journal. Follow her on Twitter @AnneTergesen .