Should You Buy the Vanguard S&P 500 ETF Right Now or Wait for a Stock Market Correction?

The Vanguard S&P 500 ETF (VOO -0.33%) is one of the best ways to invest in the S&P 500, which has been a pretty smart strategy over the long term. Since 1965, the S&P 500 has produced a total return of 10.2% annualized. The Vanguard ETF has an expense ratio of just 0.03%, so you get to keep most of your gains.

While there’s no guarantee that the S&P 500 will achieve the same level of performance in the future, it has historically produced 9%-10% annualized returns over most multidecade periods. Having said that, the S&P 500 isn’t too far from its all-time high (as of this writing), so it’s natural for investors to wonder whether now might be a good time to buy shares in an S&P 500 index fund or if it would be smarter to wait for a better opportunity.

Just under an all-time high

The S&P 500 and several other major stock indices have reached all-time highs this year and remain close to record levels. In the case of the S&P 500, the index is less than 3% below its all-time high, as of April 29.

^SPX data by YCharts.

Should you wait for a correction?

One important thing for all investors to learn is that timing the market is impossible. And quite frankly, it’s unimportant if you’re investing in a high-quality S&P 500 index fund for the long term. Even if you buy at a market peak, your long-term returns should likely be excellent.

For example, let’s say you invested in the S&P 500 at its peak in 2007 — just before the financial crisis sent the market plunging. By the time the S&P 500 bottomed in early 2009, it had lost about 50%. So this would seem like a pretty awful time to invest.

However, you might be surprised to learn that if you had invested in an S&P 500 index fund at the worst possible time before the 2008-2009 financial crisis, you would be sitting on a 355% total return today. If you look at the chart below, the actual 2008-2009 stock market crash barely looks like a blip over the long run. And that’s the point.

^SPXTR data by YCharts.

It’s also worth noting that just because the S&P 500 is near an all-time high doesn’t mean it can’t go even higher. Many people were “waiting for a correction” in the 2014-2015 time frame after a long post-financial crisis rally and never got one.

A better strategy

Having said that, the best way to invest in S&P 500 ETFs is a little at a time, not all at once.

One excellent strategy is to invest equal amounts of money at certain intervals. This is known as dollar-cost averaging, and mathematically, it guarantees that you’ll buy more shares when prices are lower and fewer shares when prices are high.

As a basic illustration of this, let’s say you plan to invest $1,000 in the Vanguard S&P 500 index fund every three months. Right now, the fund is trading for approximately $470 per share, so assuming your broker allows you to buy fractional shares, you’d buy 2.13 shares of the index fund.

Now let’s say that a market correction comes, and the share price of the fund falls to $430 by the time you’re ready to make another investment. This time, your $1,000 investment will buy 2.33 shares.

The bottom line is that by averaging into a fund like the Vanguard S&P 500 ETF, you’re going to get a favorable average share price over time. A strategy like this is a far better way to invest than trying to decide whether to invest a lump sum now or later.