Geopolitical issues have riled the markets, which is actually a pretty common thing on Wall Street. However, that doesn't make it any easier to live through the volatility.

If it has been hard for you to sleep at night, you might want to take a look at this exchange-traded fund (ETF) that tracks an index designed to select financially strong, growing, high-yield stocks. Here's what you need to know.

You've probably never heard of this index before

The interesting thing with index-based ETFs is that the indexes they track are often created with the sole purpose of giving the ETF an index to track. That's likely the case with Dow Jones U.S. Dividend 100 Index. This is the index that the Schwab U.S. Dividend Equity ETF (SCHD 1.07%) tracks. Other than the word dividend and the number 100, there's not much here to tell you what this index does or why you should be interested in it.

Image source: Getty Images.

When creating the index, one of the first steps is to eliminate real estate investment trusts (REITs), which are designed to pass income on to investors. They would probably dominate the portfolio if included, so this makes sense. The next step is to only consider companies that have increased their dividends for at least a decade. A company has to be fairly well run to have a dividend streak that long.

Some indexes might stop there, but not the Dow Jones U.S. Dividend 100 Index.

The real investor benefit is in the composite score

The next step for the index is to create a composite score that looks at cash flow to total debt, return on equity, dividend yield, and a company's five-year dividend growth rate. Running through this list quickly, cash flow to total debt examines financial strength, return on equity provides a view of how well a company is run, dividend yield is the income it currently generates for investors, and the five-year dividend growth rate is an indication of recent growth trends for the dividend and, indirectly, the business.

SCHD Dividend Yield data by YCharts

The big story is that, while you may look at different statistics, you would probably be considering similar factors if you were buying individual dividend stocks. Basically, the Dow Jones U.S. Dividend 100 Index is very likely doing what you would do.

Once the composite score is created, the 100 highest-scoring stocks get into the index. And you buy this index when you buy the Schwab U.S. Dividend Equity ETF. The expense ratio is a tiny 0.06% and the dividend yield is a well-above-market 3.7%. And since the portfolio is updated annually, you will always have the best-scoring companies in the portfolio with no extra work on your part.

SCHD Dividend data by YCharts

Schwab U.S. Dividend Equity ETF is not the highest-yield ETF you can buy. It is not the best-performing ETF you can buy. But it has proven to be a very reliable dividend payer, with a dividend that has trended higher over time. If you are a dividend investor looking to own reliable dividend growers, this ETF provides a good balance between income, risk, and reward.

Schwab U.S. Dividend Equity ETF is accessible

Schwab U.S. Dividend Equity ETF recently enacted a 3-for-1 stock split, which brought its share price down materially. Thus, you can buy the ETF's units for around $25 or so each. In other words, it doesn't require a huge amount of money to add this ETF, and the well-thought-out index backing it, to your portfolio today.