Every few days, there’s yet another revelation of a mutual- fund company coming under regulatory scrutiny for allowing favored investors to take advantage of rank-and-file shareholders. And with the Securities & Exchange Commission demanding more information from 88 fund management companies, it’s unlikely that we’ve heard the last of the transgressions. That leaves the nation’s 95 million fund shareholders in a quandary over the $7 trillion they’ve entrusted to the fund industry. What’s an investor to do? Here’s a guide for worried investors.

If one of my funds is implicated in the scandal, should I sell?

Your visceral reaction may be to dump the fund, but the cost of doing so could easily make any losses worse. Selling shares (except in a tax-deferred retirement account) is a taxable event, so if you’ve owned the fund for a long time and have built up capital gains, you could be hit with a tax bill.

What’s more, if you bought the fund through a broker and have B shares, you might be liable for a stiff exit fee as well. (B shares have no initial sales charge, or load, but recoup the broker’s commission through higher annual fees and redemption charges.) And if the fund is part of an asset-allocation plan, you shouldn’t sell unless you have a suitable replacement. If you’re worried about fund oversight, you can be sure it’s going to be tougher in the future than it has been in the past.

Are there any circumstances in which I should now consider selling?

The only reasons to consider are the standard ones. If the fund has been underperforming its peers consistently, it’s time to think of switching to another. Alternatively, if your investment goals have changed and the fund no longer meets your needs, you should find something more appropriate.

How can I tell if a fund has allowed market timing or given special favors to others at my expense?

You can’t. That’s why the regulators are now poring over fund company documents and data. Still, there are some signs that may indicate a problem, such as a sudden jump in portfolio turnover, a measure of trading activity. Suppose a fund with $500 million worth of trades in a year and $1 billion in assets has a 50% turnover rate. (You can find the ratio in prospectuses and financial reports.)

What happens if the turnover rate triples? It could be a sign of rapid-trading market-timers in action. But it could also be the result of a change in investment strategy. Or perhaps there’s a new portfolio manager at the helm.

Are some funds more likely to be involved in the scandal?

International equity funds have been hit hard, mainly because of a quirk in their pricing. For instance, the Asian markets close before Wall Street opens, yet you often can buy an Asian fund until 4 p.m. New York time. If something happens during U.S. trading hours that’s likely to affect foreign markets, timers can buy these foreign funds at old prices unless the funds block them.

As far as “late trading” goes — letting some investors buy or sell at yesterday’s price — that could happen with any sort of fund. Most of those involved so far, though, are U.S. growth stock funds.