With many exchange-traded funds, it's easy to predict how they'll perform. If you have an S&P 500 index ETF, for instance, all you have to do is look at the S&P's closing value to get a sense of how your fund did. Even if you own a less transparent ETF like a sector-tracking fund, you might be able to get a solid sense of your performance on any given day by looking at representative stocks in that sector to see how they did. But for ETF investors looking for a single fund that can withstand any market e ...

Exchange-traded funds are designed to be building blocks that are easy to put together. You can find stock-focused ETFs of all kinds, which you can mix and match to customize your own particular exposure to stocks. You can then pepper in ETFs containing other types of investments, including bonds, commodities, cryptocurrencies, or just about any asset class you can think of.Some investors, though, would prefer to have a single ETF that would handle all of their investment needs for them. This led the fund m ...