NEW YORK -- Rebalancing investment accounts isn't exactly at the top of most people's to-do lists, which is why several new online services offer to do it for you.

One of them is Rebalance IRA (, launched in January 2013 as an outgrowth of the portfolio advice service The site has $180 million in assets under management and charges a fee of 0.5 percent to suggest a diversified mix of very low-cost index funds, and then adjusts the selections as needed.

In order to set the philosophy that guides those investment decisions, Rebalance IRA relies on an investment advisory board which includes retired Princeton economics guru Burton Malkiel as well as Charles Ellis, founder and former managing partner of Greenwich Associates, and Jay Vivian, the former managing director of IBM's Retirement Funds.

The trio meets periodically to strategize, and invited Reuters to their January investment council to discuss their secrets to investing success.

Q: How do you decide what is best for people you have never met?

Malkiel: Rather than thinking that one active manager is better than another active manager, we're putting together diversified portfolios that have different risk levels and are suitable for the people we are trying to serve. We're making sure that we are doing it in the most cost-effective manner possible. That's a difference between what we do and what most financial advisers do.

For instance, we were just having a discussion about possibly replacing one bond exchange-traded fund that we use with another, because it has just become available at a considerably lower expense ratio.

Q: That seems a very detailed decision, and not a macroeconomic discussion. Is that how deeply you focus?

Ellis: It goes to the big picture. You have to do what you can control, and that is to keep costs way down. I like to emphasize that by looking at fees not as a percentage of the assets you've already got, but as a percentage of the return. Then, all of a sudden, fees turn out to be huge.

Malkiel: And then they compound over time. The fact is, looking at what you've got left after 30 years, the difference between making 7 percent or making 5 percent after fees is that you've lost 50 percent of your growth to fees. This is not a little deal - this is a big deal.