The best way to build wealth over the long term is, arguably, to invest in the stock market. And given that the average annual Social Security benefit for retired workers this year will only be around $22,000, most of us will need to construct our own nest eggs if we want to enjoy comfortable futures. Investing is also important if we want the value of our assets to keep up with (or exceed) inflation, and if we want to set up income streams we can access without selling assets. 

A recent Motley Fool report took a look at just how many people in the U.S. own stock, and according to a recent Gallup survey, 58% of American adults -- about 150 million people -- do.

Fifteen people are shown, in a three-by-five grid, like in a Zoom call.

Image source: Getty Images.

Here's a look at some insights and takeaways from the report and Gallup data.

Why stocks?

First, let's set the stage to understand why stocks are the way to go for most investors. The table below offers the average annualized returns of various asset classes between 1802 and 2021, per Wharton Business School professor Jeremy Siegel:

Asset Class

Annualized Nominal Return









U.S. dollar


Source: Stocks for the Long Run, Jeremy Siegel.

See? It's not even close. Stocks outperformed over shorter periods, too. For example, Siegel found that between 1946 and 2021, stocks grew at an average annual rate of 11.3%, vs. 5.8% for long-term government bonds.

The stock market can be volatile, which is why average returns can vary widely over shorter periods. You can hope and plan for returns averaging 8% or 11% over your particular investing period, but you might, in fact, average 7% or 13%. It's important to only invest your long-term dollars in stocks, too, because over relatively short periods of, say, five or even 10 years, the market can underperform or drop. You want to give your money a lot of time to grow.

Here's a quick reminder of just how much you might amass via the stock market:

Growing at 8% for

$5,000 invested annually

$10,000 invested annually

5 years



10 years



15 years



20 years



25 years



30 years



35 years



40 years



Source: Calculations by author.

More than before ... but still too few

That 58% is pretty good, but that still leaves 42% of American adults not investing in stocks. It's worth noting that this rate has been rising and falling: As few as 52% of American adults were stock investors in both 2013 and 2016, and as many as 63% were stock investors in both 2002 and 2004. The rate has been rising in recent years.

With any luck, the share of Americans who own stocks will keep rising -- and that's more likely to happen soon if the U.S. doesn't enter a recession and perhaps if interest rates and inflation fall. (The inflation rate has in recent months been slowing down, though a report released on Feb. 24 found core consumer prices were 4.7% higher in January than they were a year ago, topping expectations for a core inflation rate of 4.3%.)

How to invest in the stock market

If you're already investing in stocks, great! Consider investing larger sums regularly if you can in order to grow your nest egg faster.

If you're not yet invested in stocks, you might reasonably be wondering: How do I start? It's probably easier than you think. You might see if your workplace offers a 401(k). If it does, see if its investment menu includes any index funds, such as those that track the S&P 500. If not, you can open a regular taxable brokerage account or a tax-advantaged IRA account and invest in a good, low-fee index fund through that.

Index funds simply hold roughly the same securities as the index they track -- and in the case of an S&P 500 index fund, it would hold shares of 500 of America's biggest publicly traded businesses. Such funds offer a simple -- and powerful -- way to invest in stocks, and you'll end up with close to the same return as the overall stock market.

If you want to try for even bigger gains, you'll need to read up on investing and learn how to evaluate companies. It will take some work, but it's also not rocket science. For most people, though, it's hard to beat the ease and effectiveness of index funds.

However you go about it, be sure you're among the 58% of American adults investing long-term money in stocks.