I've Owned the Vanguard S&P 500 ETF for 6 Years. Here's Why I'm Not Selling.

About six years ago, I finally converted a 401(k) from a former job into an individual retirement account (IRA). I fit the classic description of a former employee who kept putting off rolling over my account for many years, missing out on better gains because I was too lazy to do a little paperwork.

I knew I wanted an exchange-traded fund (ETF) in the new IRA, and it was a pretty easy decision to choose the Vanguard S&P 500 ETF (NYSEMKT: VOO) and never sell. Here's why.

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1. It has one of the lowest expense ratios around

Vanguard ETFs are known for their low expense ratios, which are the annual fees you pay for the fund. All funds charge a fee, but Vanguard's are the lowest in the business, and the Vanguard S&P 500 ETF charges just 0.03%.

This means that for every $10,000 you have invested in the fund, you'll pay just $3 annually. That's incredibly low, and it allows you to keep more of your fund's returns compared to other ETFs. Consider that the average expense ratio for passive funds (which Vanguard's S&P 500 ETF is) is 0.14%, and actively managed ETFS cost an average of 0.44% annually.

2. The S&P 500's track record is pretty impressive

With Vanguard's S&P 500 ETF tracking the index, the fund taps into more than 500 of the largest publicly traded companies in the U.S. There's no such thing as guaranteed returns for any stock or any ETF, but the S&P 500 (SNPINDEX: ^GSPC) has a long history of delivering impressive returns. Since 1956, the index has had a historical average return of about 10%.

Many investors get so focused on beating the market that they forget that putting money consistently into an S&P 500 ETF -- and letting growth compound over decades -- is a very good strategy for reaching your retirement goals. For example, here's how $10,000 initially invested in the S&P 500, including regular contributions, and an average annual return of 10%, grows.

Data source: Author's calculations.

Everyone's investment goals are different, and there's certainly no guarantee you'll earn 10% every year with an S&P 500 ETF. But the figures above show that, based on historical averages, you can grow $10,000 into a considerable sum with consistent monthly contributions.

3. I don't have to worry about following trends

The Vanguard S&P 500 ETF isn't the only investment in my IRA. I also own individual stocks, but owning the fund lets me benefit from the S&P 500's broad diversification.

Instead of chasing trends, worrying about which part of the economy is growing and which is retracting, or trying to time the market, I simply keep a sizable amount of my portfolio in the Vanguard S&P 500 ETF. This allows me to benefit from technology stocks when they're surging higher -- as artificial intelligence stocks have been over the past few years -- and other areas of the market if they begin growing.

It also means that if a bear market comes around soon, I don't have to worry about rotating out of some stocks. Instead, I'll continue to own the Vanguard ETF, knowing I'll be able to catch the next wave of growth, no matter which area of the market rebounds faster.

Chris Neiger has positions in Vanguard S&P 500 ETF. The Motley Fool has positions in and recommends Vanguard S&P 500 ETF. The Motley Fool has a disclosure policy.