Every now and then I write a column urging investors to steer clear of mutual funds that charge “loads,” which are up-front sales commissions that can run to 1, 2, 3, even 5 percent of the amount invested. There are so many funds out there you can always find a comparable fund that doesn’t charge a load.

This argument always draws phone calls, letters and e-mails from unhappy stockbrokers. The load, they contend, is fair compensation for the work they do in steering customers to suitable funds. Invariably, they argue there are lots of excellent load funds.

So I ask for a list. Tell me which funds are likely to beat the no-load competitors. Give me the list, I’ll put it in a column and identify you as its author, I tell the disgruntled brokers.

I promise to follow up in six months or a year to tell readers how those load funds have done.

Well, you haven’t seen this list in the paper. No broker has accepted the challenge. The fact is, load funds are a bad deal. Loads are meant to benefit brokers, not investors.

Pay a 5 percent load on a $10,000 investment and you start with only $9,500. You’ve got to make 5.26 percent just to break even ($9,500 times 5.26 equals $499.70). And if the fund loses money — well, paying the load must makes things worse.

Now the case against loads has gotten even stronger.

Investors who put in large amounts are entitled to volume discounts on loads. But it turns out that many of these folks aren’t getting those discounts. That was the finding after a three-month study by the Securities and Exchange Commission, the National Association of Securities Dealers and the New York Stock Exchange.

Their investigators examined mutual fund transactions from November through January at 43 brokerages. They found that about a third of the customers who were entitled to “breakpoints” — volume discounts on loads — didn’t get them.

While the investigators labeled most of the errors as inadvertent, you wonder why these firms didn’t have better systems for making sure customers weren’t overcharged. Well, if the customers don’t notice and it puts more money into the firm’s coffers …

Using simple arithmetic, it’s possible to make a case for some load funds, on paper. If you are going to own a fund for a very long time, it might be better in the long run to pay an upfront load if, in exchange, you are charged less on other fees.

These fees, such as the charge that pays the fund’s professional managers, are wrapped up in a fund’s “expense ratio.”

Among the thousands of funds out there — load and no-load alike — annual expenses range from less than 0.2 percent of the amount you have invested, to 1 percent, 2 percent, even more.

To further complicate things, many load funds sold through brokers come in various classes, and the investor can choose: a big up-front load and small expense ratio, no load and large ratio, or something in between. In theory, the trick is to figure which combination will pay off for you, based on how long you expect to own the fund.

As I said, that’s an argument on paper. In real life, the longer you expect to own your fund the less likely there will be any benefit to paying a load. Here’s why:

Load funds are “managed” funds — the kind that employ teams of pros to hunt for hot stocks. Research shows that most fund managers who do well in any given year are just lucky. In other years, they are unlucky. The longer they are at it, the more likely their results will be no better than average.

For the small investor to do well with managed funds, she would have to quickly pull her money out of the ones that are no longer doing well and put it into the ones that are turning hot. Unfortunately, almost no one can spot these perfect moments to switch.

Even if you — or your broker — could do it routinely, your gains would be chewed up by all the extra loads you’d pay.

For an extreme example, imagine you started with $10,000 and moved to a new fund every year, incurring a new 5 percent load every time. That means that in order to simply match the performance of the market overall, your fund manager would have to pick stocks that, altogether, beat the market by 5 percentage points a year. That would be an extraordinary achievement. In fact, it would be virtually unprecedented.

So here are the two facts to keep in mind with load funds:

You can only justify paying the load if you hold the fund for a long time.

But the longer you hold the fund, the less likely it is that it will continue to provide the market-beating returns that made it attractive in the first place.

That’s what they call the horns of a dilemma.

There’s just no point in paying a load. Indeed, I doubt it makes much sense to invest in managed funds at all. Not when you can easily guarantee yourself market-matching returns with simple index funds that buy and hold the stocks in well-known indicators such as the Standard & Poor’s 500. They have no loads and rock-bottom annual fees.