I buy my mutual funds directly from the mutual fund company. Would it be more advantageous to trade them through my brokerage account online? If a mutual fund I own suddenly has poor performance or a management change, it seems to me that it would be better to sell the fund online, so that I can conduct the transaction quickly. - K.C.

The do-it-yourself investor has a couple of options for investing in mutual funds besides a 401(k) plan. You can invest through the mutual-fund companies themselves. Or you can invest through a mutual-fund "supermarket" like Charles Schwab or Scottrade, where you can buy lots of funds from different companies in one place. Some large fund companies offer their own supermarkets where investors can choose from among that firm's funds in addition to those from other no-load fund companies.

The joy (and pain) of one-stop shopping: One of the reasons that investors have flocked to mutual fund supermarkets is for simplicity. Let's say you own six funds from six different fund families. If you had to deal directly with each fund company individually, you'd have to fill out six separate forms to open each account. You'd have to send money separately to each firm when you wanted to add to your investments. And think about the mail you'd receive! Each firm would have to send you a separate statement about your investments.

By contrast, if you open a brokerage account through a mutual fund supermarket, you're usually able to access a variety of no-load funds through one place. You have only one account to manage, which can help simplify your investment decisions. Also, you can sometimes access high-minimum funds for less through a mutual fund supermarket. For example, if you want to buy Weitz Value (WVALX) directly, you'd have to pony up $25,000. But some supermarkets allow you to make an initial investment in the fund of only $2,500.

Supermarkets can be really appealing, no question, but make sure you read the fine print. Some supermarkets charge a transaction fee for funds that aren't part of an "NTF plan." (NTF stands for "no transaction fee.") If you can buy a fund through a supermarket without paying a transaction fee, it can be a really good deal.

However, if you have to pay a transaction fee, it can be quite expensive. The transaction fee is usually a flat fee, so if you're investing a small amount - say $100 or $500 - and the transaction fee is $35, that's a huge portion of your investment. It can be really problematic if you want to build your investments by dollar-cost averaging (investing a small amount every month).

So if you're interested in a supermarket, look at the list of fund families that participate in the NTF program. If you see a lot of funds you like, that supermarket might be a nice option; however, there are also the costs of the brokerage account itself, which you should investigate. Different firms charge different amounts to maintain the accounts. And some charge an arm and a leg if the account falls below a certain amount.

Speed is not a factor: What about K.C.'s other question - faster service through a brokerage account? The answer is generally no. For one thing, a lot of mutual fund companies allow you to buy and sell your funds online these days, just like the big supermarkets. And even if you can't conduct the transaction online, you can always call the fund company. Either way, it shouldn't matter much. You see, fund transactions only occur at the close of business for that day. So whether you call your fund company at 10 a.m. to buy one of their funds or make the purchase over the Internet at 12:30 p.m., the sale should take place at the end of the day.

In addition, immediacy isn't usually critical when buying and selling open-end mutual funds. Let's say something bad happens to your fund: The superstar manager quits in a huff.

The fund isn't going to plummet 50 percent in a day just because the manager left. It can't, because the fund's NAV - its daily "price" - is simply a reflection of the value of the fund's underlying securities. (If you want to know more about NAV, my colleague Peter Di Teresa wrote an article about the topic.)

To be sure, you might want to sell the fund if the manager leaves, but you shouldn't necessarily feel pressured to dump the fund the day the news hits the airwaves.

You can take a little time to decide whether you really want to sell or not. In this way, mutual funds are very different from stocks, where you might find that you want to unload plummeting shares in a hurry if a company is in serious trouble.