You, essentially.

You the investor. You the day trader. You the pension beneficiary. Whether directly or indirectly, households own the stock market.

But the inequality of this ownership is simply incredible. Broken up by income percentiles, here's how ownership of the stock market spreads out:

Source: Levy Institute 2007, author's calculations.

A lot of the reason for this inequality is cause and effect. Wealthy people don't own stocks because they're wealthy; they're wealthy because they own stocks. Go down the annual Forbes list of billionaires. It's predominantly a list of folks who have made their fortunes through stock market appreciation. From Bill Gates with Microsoft (NYSE: MSFT) to Warren Buffett with Berkshire Hathaway (NYSE: BRK-B) to Sergey Brin with Google (Nasdaq: GOOG), the wealth of most billionaires is married to the stock market in one way or another. The top 50 billionaires include those overwhelmingly linked to the performance of Wal-Mart (NYSE: WMT), Dell (Nasdaq: DELL), and Amazon (Nasdaq: AMZN) stock, to name a few.

But it's worth asking: Is this wealth inequality a good thing? Should we be proud of it? There are two ways, I think, of looking at it.

One, inequality could be seen as a sign of opportunity. There's massive inequality in this country because it's possible to work hard and grow far wealthier than most of your peers. And that's great.

But an interesting counter to this point comes from a recent report by the Organization for Economic Cooperation and Development, which shows the United States has one of the lowest rates of social mobility -- basically, the ability to move from poor to rich -- in the developed world. Put simply: "Intergenerational social mobility tends to be lower in more unequal societies." One reason for this, the report notes, is that "there is a substantial wage premium associated with growing up in a better-educated family, and a corresponding penalty with growing up in a less-educated family." In the U.S., nearly 50% of someone's earnings can be explained by his or her parents' earnings, compared with less than 20% in Canada, Finland, Norway, Australia, and Denmark.

It's a trade-off, then. In one sense, our wealth inequality is a sign of opportunity. In another sense, that opportunity has a tendency to be based on privilege and heredity.

What do you think?

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.