The Economic Policy Institute (EPI) think tank recently released some preview data from "The State of Working America 2004/2005." The numbers aren't pretty.

It may be true that over the past few decades more and more Americans have become stockholders, but not enough have. Apparently, and shockingly, the top 1% of shareholders own nearly half of the entire stock market's value. Here are some other findings:

  • Half of American households don't hold stock (48% in 2001) -- not in regular brokerage accounts, not in IRA accounts, not in pension plans, and not through mutual funds.

  • The EPI's stock ownership information is based on data compiled by New York University economics professor Ed Wolff, who found that the wealthiest 1% of all households control more than 33% of national wealth, while the bottom 80% of households have only 16%.

  • Many stockholders don't own much stock at all: "Only 40.1% of Americans held stock worth more than $5,000."

  • The bottom 80% of Americans own only 11% of all stock market holdings.

  • The wealthiest 1% owned an average of about $3.5 million worth of stocks. The least wealthy 40% of households owned just $1,800 of stocks.

Kudos to those who own even $1,800 of stock in an environment where so many own so little and so many more owe so much. But still, if $1,800 grows at 10% per year for even 40 years, it will become merely $81,500 -- not enough to do much with in 2044, probably.

What does all this data mean? Well, for those with insufficient savings and investments, retirement is a precarious proposition. They'll likely be relying mostly on Social Security, which may or may not be there when needed and may well not provide the degree of support expected or needed.

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Stock investors should know that they're using what is arguably the most effective wealth-building mechanism there is. A CBS MarketWatch article on the EPI results reported, "For the middle 20% of families with average net wealth of $75,000, the stock market wealth tripled between 1989 to 2001 from $4,000 to $12,000."

Consider forwarding this article to any people you care about who aren't stock investors -- they may thank you for it later. (Just click on "Email this Page" near the upper-right corner of this page.) And if you're ready to jump into investing now, consider an index fund first. A simple S&P 500 Index fund will immediately have you invested in the likes of General Electric (NYSE:GE), ExxonMobil (NYSE:XOM), Citigroup (NYSE:C), and Merck (NYSE:MRK).

Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article.