The stock market is shaking off everything from war to inflation, with the S&P 500 index generating a nice 13% for investors this year.

But a rocky stretch may be coming, and it could pay to protect yourself.

September and October are the two most volatile months for the market. September is the only one averaging a net negative return, going back to 1928. As for October, its ignominious milestones include the crashes of 1929 and 1987.

On the top level, the stock market hasn't been particularly choppy this summer. The Cboe Volatility Index, or VIX, stands around 15, slightly below its historical average. Companies just wrapped a stellar second-quarter earnings season.

But it hasn't been a smooth ride. Semiconductor stocks plunged more than 18% in late July. In the bond market, yields have risen on inflationary pressures stoked by the Iran war and higher energy prices. Investors are still trying to figure out Federal Reserve Chairman Kevin Warsh, who had a rocky first news conference.

What's more, the classic 60/40 portfolio has become more volatile. Bonds are supposed to provide ballast when stocks decline, but that relationship has broken down in recent years. Stocks and bonds are now more correlated, weakening "the relationship that has historically supported diversification," according to a BlackRock analysis.

That doesn't mean you should ditch bonds or a classic balanced portfolio. The iShares Core 60/40 Balanced Allocation exchange-traded fund, for instance, is up 9% this year. It returned an annualized 8% over the past decade.

Still, retirees who get nervous when the market gyrates or count on cash withdrawals from their portfolio may want to take protective measures. "Retirees are grappling with the portfolio being their business, their paycheck, so every bump feels more material," says Alex Guiliano, chief investment officer at Resonate Wealth Partners in Ridgewood, N.J.

Keep a Cash Cushion and Invest It

You don't want to be forced to withdraw from a declining stock portfolio to pay daily living expenses. That will drain your money much faster than if you're able to leave your portfolio alone until the market recovers.

Build a cash cushion of at least a year's worth of withdrawals -- the amount you need to meet living expenses after Social Security or other pension payments. Many advisors recommend an even bigger cushion, if possible, in cash or equivalents like money-market funds.

Yields are relatively high, moreover, so you can earn some income off your cash. Money-market funds from brokerages like Fidelity, Vanguard, and Charles Schwab yield about 3.5% right now. Short-term bond funds yield a little more, though they aren't as rock-solid as money markets.

Diversify Within Equities

It's anyone's guess whether the market's infatuation with artificial intelligence will continue. If it doesn't, the damage will extend beyond tech, affecting many other sectors and even funds that emphasize "value" stocks.

But a tech pullback doesn't have to spell doom for your portfolio. Market breadth has improved, and it's important to be diversified to take advantage of the more diffuse gains.

The S&P 500 Equal Weighted index is up 16% this year, versus 13% for the traditional market-cap-weighted S&P 500. Funds like the Invesco S&P 500 Equal Weight ETF own stocks in equal proportion and may help ease the sting if the AI-related giants falter.

Don't sleep on international stocks. Many advisors recommend that investors allocate at least a quarter of their equity exposure outside the U.S. The iShares MSCI ACWI ex U.S. ETF is a low-cost way to get exposure. About 20% of its assets sit in tech, with about half in Korean chip stocks like Taiwan Semiconductor Manufacturing and Samsung Electronics, but it's diversified globally and may hold up better in an AI-related selloff.

Consider an Annuity

Annuities tend to get a bad rap due to historically high fees and complexity. But these insurance contracts come in many different flavors and prices. The right one can help temper volatility and extend the life of your savings. Check out Barron's recent roundup of the best annuities.

A popular choice is a fixed indexed annuity with an income rider. Fixed indexed annuities offer protection against market downturns by limiting upside in a bull market. With an income rider, there's the option to turn on an income stream at any time and collect guaranteed income for life. Fees may be built into the caps or presented separately and are usually in the 1% annual range, says Mike Downing, co-president of Athene USA, an insurance provider. One shouldn't replace your stock portfolio, but you could consider buying one with a portion of your equity sleeve.

Any insurance product can be costly over time if you don't wind up making good use of its benefits. You'll be happy you have it, though, if the AI party ends with a bang.