Facts, facts, facts. Journalists love them. And every May, the mutual fund industry obliges with a new “Fact Book” from the Investment Company Institute, the industry’s trade group.

I’ve been reporting on these in this column for 12 years, but this is the last time. I left the Philadelphia Inquirer in January and agreed to write several columns as a freelancer. This is the last.

The great thing about being a columnist is the way readers respond. Thank you for the thousands of letters, e-mails and phone calls over the years. I’m not retiring my keyboard. Google me and you’ll find new thoughts on personal finance and investing in all sorts of places. Or write to jeffbrown@jeffbrownfinance

.com.

The 47th “Fact Book” edition, out last week, is full of data on the soaring growth of this industry – $10.4 trillion in fund assets at the end of 2006, up from $4.5 trillion a decade earlier.

But two sets of data stand out.

First, most individual investors – 73 percent – turn to brokers or financial advisers for help with choosing funds.

Having spent so many years writing a column for do-it-yourselfers, I have to confess to a little frustration over this. It’s easy to shop on your own on the Web, to deal directly with a fund company and avoid the fees you’d have to pay for professional help.

The second set of data makes the picture even darker.

It traces the flow of money into and out of funds, and compares that with the ups and downs of the stock market.

The resulting chart vividly shows that investors pour money into stocks when the market is doing well and pull money out when it does poorly. Investors, for example, added more than $309 billion to stock funds when share prices were soaring in 2000, and pulled out $27.6 billion in 2002, after the tech-stock bubble burst and prices had collapsed.

In other words, investors buy high and sell low – exactly the opposite of what they ought to do.

Why are investors doing this if three-quarters of them are getting professional advice? What are the pros telling them?

Many, I’m sure, are offering perfectly sound advice that’s being ignored. But the numbers are so stark that there must be a lot of advisers guilty of the same rearview-mirror behavior as their clients are.

A number of recent studies have shed new light on the price investors pay for this.

The standard way to measure mutual fund returns is to look at what would have happened, for example, if one invested $10,000 five years ago and left it alone. If the investment grew to $15,000, it would be a 50 percent return over five years.

Morningstar, the investment-data company, last year started reporting an additional figure for each fund – “investor return.” It looks at what happened to all the fund’s investors taken together, focusing on when money flowed into and out of the fund. The data confirmed the widespread buy-high, sell low behavior.

Following the mob is dangerous. So how do you guard against an adviser who does it?

Insist on a strategy that will put the bulk of your money into investments that you will hold for at least five or 10 years, avoiding the sucker’s game of short-term speculation.

Ask how the adviser will gauge your investments’ performance. Each holding should be assessed alongside an appropriate index, such as the Standard & Poor’s 500 for stocks of big companies, or the S&P 600 for stocks of small ones.

Don’t give your adviser authority to buy and sell for you on his own. You should be consulted on every step and you should ask lots of questions, such as why do this? Why now? Why this fund instead of another in the same category? Are there competing funds that are more tax efficient and have lower fees?

Understand all the commissions and other fees you’ll be charged. If they total 2 percent or 3 percent of your portfolio’s value each year, it’s a red flag – a cost that will chew deeply into your long-term returns. By dealing directly with a fund company, you could keep those costs well below 1 percent.

Assess what are you getting for these fees. Bigger returns than you could get on your own? Less risk? Some help with tax issues or estate planning?

Finally, don’t be afraid to jump ship. If your adviser turns out to be a fad follower or can’t produce enough extra return to offset his fees, find someone else.

Or run things yourself.