Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add a bunch of extra-promising mid-cap companies to your portfolio, the Guggenheim Mid-Cap Core ETF
ETFs often sport lower expense ratios than their mutual fund cousins. The Guggenheim ETF's expense ratio -- its annual fee -- is 0.68%, which is a bit steeper than that of many ETFs, but also considerably lower than that of the typical stock mutual fund. The fund is small, too, so if you're thinking of buying, beware of occasionally large spreads between its bid and ask prices. Consider using a limit order if you want to buy in.
This ETF has performed well, outperforming the S&P 500 over the past three and five years. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.
What's in it?
Plenty of mid-cap companies that this ETF invests in had strong performances over the past year. Delta Air Lines
Other companies didn't do as well last year, but could see their fortunes change in the coming years. It's hard to find a more dependable industry than garbage collection and recycling, so no one should write off Republic Services
Check Point Software Technologies
The big picture
A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier. For some compelling investment ideas, check out our special free report, "3 ETFs Set to Soar During the Recovery."
Longtime Fool contributor Selena Maranjian, whom you can follow on Twitter, holds no position in any company mentioned. Click here to see her holdings and a short bio. The Motley Fool owns shares of Check Point Software Technologies. Motley Fool newsletter services have recommended buying shares of Check Point Software Technologies and Republic Services. The Motley Fool has a disclosure policy.