INVESTOR'S NOTEBOOK by Brendan Boyd

(A digest of investment opinion from the world's leading financial advisers)

If you are a mutual fund investor and want to sock away $150, you simply send your fund company a $150 check. But it's considerably harder for stock investors to buy in small, round dollar amounts. At most brokerages, the closest you could get to $150 with a $20 stock is seven shares for $140, not counting commission charges. And if you were interested in a $160 stock, you couldn't buy in at all.

Until now, says money.com.

"Several specialty online brokerages have begun offering the opportunity to invest in stocks in dollar increments rather than shares, a particularly attractive strategy to those just starting out, or to anyone who doesn't want to put up a lot of money in a single trade."

Here, according to money.com, are the three leaders in this incremental revolution:

(1) Buyandhold.com

With just $20, you can open an account at Buyandhold.com and then choose from 1,400 stocks and three index-based shares: SPDRs, Diamonds and the Nasdaq 100. Unlike most brokerages, Buyandhold.com bundles customer orders together and places block trades twice a day. This keeps commissions down to $2.99 per transaction, says money.com.

"Buyandhold.com also lets you automatically reinvest your dividends and set up regular deposits, so you can have a fixed dollar amount withdrawn from your checking account on a weekly, monthly or quarterly basis and invested in any stocks you choose."

(2) ShareBuilder.com

ShareBuilder operates almost identically to Buyandhold.com; only the particulars of fees and policies differ. ShareBuilder offers a wider selection of securities, with 2,000 stocks and 23 index-based shares. Though its flat transaction fee is $5 for one-time investments, it drops to $2 for recurring investments in regular accounts (and $1 in custodial accounts). Some of ShareBuilder's policies emphasize a buy-and-hold approach even more than Buyandhold's. ShareBuilder executes trades only once a week, for example, making it even harder to capitalize on short-term fluctuations in a stock, notes money.com.

"Also, while Buyandhold.com charges a flat $2.99 whether you're buying or selling, ShareBuilder charges a comparatively punitive $19.95 to unload an investment."

(3) FolioFN.com

Founded by former SEC commissioner Steve Wallman, FolioFN offers something different. For $295 a year, you get access to unlimited trades (executed twice a day) in what the company calls "folios," or pre-set baskets of as many as 50 stocks assembled to represent a particular industry, index or risk tolerance. Or you can assemble your own basket, stock by stock, using FolioFN's screeners. While the idea is innovative and the folios could provide easy diversification, pricing here may not be the best value for many investors, concludes money.com.

"Unless you can commit more than $10,000 and you plan to actively manage your money between baskets, the $295 tariff (almost 3 percent on $10,000) is probably too steep. You'd be better off diversifying with index funds."

(Investor's Notebook reflects the opinions of professionals. It does not recommend any specific investments, and no endorsement is implied or should be inferred. For more information, contact the individual firms cited.)