You do all your fund shopping under one roof and get statements and tax information from one source instead of many. And no more wiring money from one fund company to another. But seven years after Charles Schwab started the first fund supermarket at the discount brokerage that bears his name, the disadvantages of supermarkets are apparent, too. Funds available at supermarkets without transaction fees typically carry higher expense ratios than other funds. Online brokerages that also serve as fund supermarkets are so overwhelmed with stock traders that they can be difficult to contact by phone.
Incidental fees are a nuisance at many supermarkets, and infuriating at a few.
Many supermarkets still don't tell you the cost basis of investments you make with them. That's vital information when it comes time to sell and pay taxes, and difficult to determine on your own without special software. In sum, you may end up wishing you'd never opted for one-stop shopping. And maybe you shouldn't. Odds are you'll get better personal service over the phone when you need it, and you'll avoid some of the aggravating fees that sneak in among the supermarket aisles.