In the space between DIY investing and personal — but expensive — financial advisors sits the robo-advisor, a crop of companies that manage client portfolios via computer algorithms, cutting costs and passing the savings on to investors.

Robo-advisors are advisors like wireless phone company telephone prompts are communications consultants.

Last month, both Charles Schwab Corp and Fidelity Investments unveiled so-called "robo" advice programs that offer free or very cheap algorithm-driven portfolio management to investors. …Fidelity said on Oct. 15 that it would refer its advisers who wanted a low-cost automated investment offering to Betterment, one of the largest of the new robo-advisers.