From Greg Wilson, chief analyst, the Legacy Portfolio: It’s now possible to nickel and dime your way to wealth…

“Acorns” is a proactive app that turns your spare change into an investment portfolio. All you do is link your debit and credit cards to the app.

Every time you make a purchase with a linked card, Acorn rounds the transaction up to the nearest dollar and deducts the difference. The “round-ups” are then deposited to your investment account.

[A “round-up” is the virtual spare change captured from rounding up a transaction to the nearest dollar.]

You can invest the funds in one of five diversified portfolios designed by Nobel Prize winning economist (and father of Modern Portfolio Theory) Dr. Harry Markowitz.

Acorns is a great way to monitor your spending, increase your savings, and build your investments.

Here’s what you need to know before you get started:

1. You will need to download the Acorns app. It’s available for both Apple’s iOS and Google’s Android systems. (A Web-based version is currently in development.)

2. Like other investment services, the app requires personal information, such as your Social Security number and bank account information.

3. You can link as many cards as you like. They provide a searchable list of financial providers.

4. In addition to round-ups, you can also deposit lump sums or set up recurring deposits. Dividends are automatically reinvested in your portfolio.

5. Acorns uses six highly liquid, low-expense ETFs to recommend personalized portfolio choices (see chart below).

6. A series of questions determines the best portfolio for your risk profile. The app recommended a “moderately aggressive” portfolio for me:

(You also have the option of selecting your own portfolio risk profile.)

7. Acorns charges $1 per month for accounts under $5,000, or 0.25% per year for accounts over $5,000.

8. You can withdraw your money whenever you want with no limits on how much. It takes 5-7 business days to process.

9. Right now, the service is available only in the United States. You can be sign up to be notified when Acorns is available in your country.

For more information, or to sign up for Acorns, click here.