The Wall Street Journal, Businessweek, and other major business publications are reporting that the Securities and Exchange Commission is poised to propose new rules for shoring up the $2.7 trillion money market mutual fund industry. The mutual fund industry isn't happy.

Paul Schott Stevens, president of the Investment Company Institute, an industry trade group, argues that the regulatory changes will "harm investors, damage financing for businesses and state and local governments, and jeopardize a still-fragile recovery."

Wow! What will the SEC propose that's so damaging? It has already instituted a number of changes backed by industry to bolster the market's stability. The next round of rules would be much stricter. For one thing, the SEC wants to scrap the funds' fixed $1 net asset value. Instead, let net asset value fluctuate the way other mutual funds do. For another, it wants funds to boost their capital, a traditional bulwark against losses in troubled times.

The industry is unhappy because a floating rate could reduce the appeal of investing in a money market mutual fund among investors seeking safety. More capital would eat into mutual fund returns. Both concerns are true. My reaction is, so what?

Here's the thing: The risks to investors that the SEC is trying to address are real. The goal is to head off a reprise of the 2008 run on the industry. The incipient flight on the money market mutual fund industry contributed to the worsening global credit crunch in 2008. Without reform, money market mutual funds can't be called an ultra-safe parking place for the average middle class saver. Instead, the mantra should be caveat emptor.

It's hard to imagine now, but the money market mutual fund was a terrific financial innovation from the Age of Inflation. In the late 1970s and early 1980s, it was the hot investment for middle-class savers. Key to the success of money market mutual funds was an industry pledge not to "break a buck." Investors were assured that a $1 investment would be worth at least a dollar no matter what. Money funds gradually evolved into a staid investment haven for cash and for the most part the pledge held.

That is, until 2008 when the $51 billion Reserve Primary Fund closed as losses on debt issued by Lehman Brothers pushed its share price below a buck. When it looked like a financial contagion would push more money market funds below a buck, the U.S. Treasury engineered a taxpayer rescue.

In light of that history, you can no longer trust the money fund mantra: "We won't break a buck." How do we know our safe savings -- the money that we rely on during really bad times like 2008 -- will be there during the next financial crisis? We don't know.

The risk inherent in money market mutual funds is why I like the idea of having fund values fluctuate. It reflects the new reality. And if the mutual fund industry wants to market funds as super safe havens then investors should demand the greater assurance that comes with a hefty capital backstop.

To be clear, I like money market mutual funds. I don't think the risk of loss is huge in conservatively managed ones. A money market mutual fund is a reasonable alternative to short-term bond funds and similar investments, depending on market conditions.

But don't ever forget that your money is at risk of a loss.

Chris Farrell is economics editor for "Marketplace Money." Send your questions to cfarrell@mpr.org.