Smart investing is all about putting time on your side, and the best investors have always done that by thinking long-term. Yet as you get older, your time horizon necessarily gets shorter. That's why most investing experts suggest cutting your portfolio allocation to stocks in favor of other types of assets, such as bonds, as you approach and enter retirement.

Yet the sad reality is that most people can't save enough to be able to afford to live off their portfolios throughout their retirement while remaining in complete safe investments. At least some growth becomes essential at that point, but with a shorter time horizon, it's valuable to clamp down on risk where you can. With that in mind, the following three exchange-traded funds have some desirable characteristics that make them appropriate even for retirees with only modest tolerance for risk.

ETF

Assets Under Management

Expense Ratio

1-Year Return

Vanguard High Dividend Yield (NYSEMKT:VYM)

$38.3 billion

0.08%

13%

iShares Edge MSCI Minimum Volatility (NYSEMKT:USMV)

$38.2 billion

0.15%

22%

SPDR Wells Fargo Preferred Stock (NYSEMKT:PSK)

$1.17 billion

0.45%

6%

Data source: Fund providers.

Dividend stocks for income and growth

One big challenge that retirees have faced lately is that bonds have extremely low yields. In fact, the average dividend yield on the S&P 500 has recently been higher than what you can get from U.S. Treasury bonds -- even if you're willing to go with a 10-year bond term and tie your money up for a whole decade.

The Vanguard High Dividend Yield ETF is just one of many funds that concentrate on high-yielding dividend stocks. The ETF's portfolio is highly diversified, with roughly 400 stocks across every industry group in the market. to offer as much of that income as possible. A current yield of 3.3% comes close to doubling what 10-year Treasuries pay currently, and the well-regarded dividend payers among the ETF's holdings have plenty of potential for future earnings and dividend growth in the future. Although recent returns have lagged the market, Vanguard High Dividend Yield's returns over the long run have shown its value to investors of all ages.

Older person working on a clay pot in a room with other pots and candles.

Image source: Getty Images.

Stocks that offer a smoother ride

Poorly timed market downturns can wreak havoc on a retirement portfolio, especially if they come early in someone's retirement. When you no longer have any income to invest toward your savings, it's harder to ride out steep declines.

In order to try to fight against market volatility, the iShares Edge Minimum Volatility ETF owns roughly 200 U.S. stocks that it identifies as potentially have less risk than the overall market. The ETF sports a track record that historically has resulted in less extreme drops when markets have turned downward, helping to cushion the blow for retirees and other risk-averse investors.

It's important to understand that even the iShares ETF doesn't eliminate the risk of loss entirely. However, if those losses are more manageable, then it can be easier for retirees to endure downturns and stick with their investment strategy. Moreover, a dividend yield of about 2% adds some income to the growth potential that holding stocks offers.

Looking for a preferred choice

Most investors stick with common stock, because it's the most available type of stock on the market. However, preferred stock offers a different type of investment exposure, with more of a focus on income. Getting its name from its preferential treatment over common stock in terms of dividends and liquidation payments, preferred stock has a lot of things in common with bonds -- but often with higher yields.

The SPDR Wells Fargo Preferred Stock ETF owns almost 170 different preferred stocks, with over half the portfolio invested in stocks issued by financial companies. The fund reports a dividend yield of 5.4% currently, which reflects the greater income available from preferred stock over its common stock counterpart. Investors can't expect preferred stocks to rise along with common stock during bull markets, but they also tend to avoid losing value even when the broader stock market turns lower.

Get the right ETFs to retire right

You can't afford to let up your guard with your portfolio after you retire. These three ETFs, however, can put your overall asset allocation  in position to keep getting growth and income from your portfolio even beyond the end of your working career.