NEW YORK (CNN/Money) — In retirement circles, they’re already calling it the Enron problem.

Like Enron, about 2,000 companies have 401(k)s jam-packed with their own stock — and employees can’t touch it for years no matter what’s happening on Wall Street.

Enron’s demise cost its employees more than $1 billion, inspiring three bills in Washington. President Bush has appointed a task force to study the pension laws and the Department of Labor is investigating. But opponents representing the interests of companies have been sharpening their swords.

A lot is at stake.

Reformists argue there should be a limit to the amount of company stock in your 401(k) because it’s too dangerous to concentrate your retirement money in just one investment. It’s a tragedy waiting to happen, they say. You might think your company’s stock is great — but that’s what Enron employees thought a year ago.

Critics of reform argue lawmakers have introduced proposals without proper research, propelled only by the heartfelt stories of Enron employees who lost everything.� A string of Washington think-tanks and lobby groups have commissioned studies to prove their point that the Enron problem is exceedingly rare. Opponents also say the federal government shouldn’t be telling individuals how to invest.

A retirement plan built on one name

A recent study by the newsletter DC Plan Investing found plenty of 401(k) plans with a dangerous concentration in company stock. Out of 219 large-company plans surveyed, 25 had stock representing 60 percent or more of assets. (Enron had nearly 58 percent in company stock.)

Three companies had more than 90 percent, including Procter & Gamble. with 94.65 percent, Sherwin-Williams. with 91.56 percent, and Abbott Laboratories. with 90.23 percent.

Dallas Salisbury, president of the Employee Benefit Research Institute (EBRI), said the Enron Problem is a rarity in the retirement world. The Washington non-profit research group estimates that of 340,000 companies with retirement plans, only 2,000 have a stock-laden 401(k). EBRI, which does not take sides on legislative issues, is still analyzing figures and did not provide a list of the companies.

Many of those stocks, like the rest of Wall Street, have been suffering, though nothing like the catastrophic losses of Enron.

Coca-Cola. for example, has 81.47 percent of its plan in company stock, while Texas Instruments has 75.65 percent, according to the DC Investing study. Coke shed 21.8 percent last year, while Texas Instruments gave up 40.9 percent, compared to a loss of 13 percent for the S&P 500. (Efforts to reach someone for comment at the companies were unsuccessful.)

Obviously, diversification is key, particularly when it’s your only source of retirement income, said John Hotz, deputy director of the Pension Rights Center, an advocacy group in Washington. The center would like to see a cap on company stock and a rule allowing employees to sell their shares much sooner.

Over the long term, however, employees have done well with owning stock in blue-chip companies. For example, Procter & Gamble outperformed the S&P 500 over 10, 15, 20, 25 and 30 years, according to spokeswoman Martha Depenbrock.

We think what happened with Enron employees was horrible, Depenbrock said. It needs to be looked at, and understood. It needs to be corrected. But until we know what happened, I can’t say what the remedy should be.

(Depenbrock says DC Investing overstated the company-stock weighting in P&G’s retirement plans — she puts the figure at 91.5 percent.)

WHAT’S WRONG WITH YOUR 401(K)?