Build an intelligent, tax-efficient, diversified portfolio for a fraction of the cost of traditional advisors. To do this, SigFig identified nine key asset classes that have the biggest impact on investment returns and let SigFig diversify your portfolio on two levels: security-level diversification by investing in asset class ETFs and market diversification by providing exposure to many different markets across asset classes. SigFig invests you in commission-free index-based ETFs from Vanguard, State Street, Fidelity, iShares and Schwab. These widely-held, seasoned ETFs are broadly diversified within each asset class SigFig focuses on: US-based stocks, US-based bonds, developed (non-US) and emerging market stocks, real estate, and short-term US Treasury securities.

SigFig charges an annual management fee of 0.25% billed monthly after the first $10K. They don't charge commission, transaction or trading fees. The only other fee is embedded in low-cost ETFs you'll own, with an average expense ratio between 0.07% and 0.15%, depending on your brokerage.

SigFig measures risk by looking at how stable investment returns have been in the past. For example, an investment of $100 whose value fluctuated between $90 and $110 over the course of the year is riskier than an investment whose value fluctuated between $95 and $105. More importantly, SigFig also looks at how different assets move at the same time — that's how diversification lowers the riskiness of your portfolio.