Additionally, USMV comes with certain restrictions, including stock weights withing 0.05% and 1.5% of the portfolio, sector weightings within 5% of the market-weighted index and a one-way turnover of 10%, Lee added.
SPLV tracks 100 stocks from the S&P 500 that have shown the least volatility over the past year, and the index weights holdings by the inverse of their volatilizes, so more stable stocks have a heavier weighing.
Looking at sector allocations, USMV seems to spread out its sector exposure, with health care at 17.9%, consumer staples at 15.9% and financials 14.9%, while SPLV has a heavier weighting in utilities 31.1% and consumer staples 24.2%.
In comparing fees, USMV comes with a 0.15% expense ratio and SPLV has a 0.25% expense ratio.
The iShares ETF is up 14.8% year-to-date and the PowerShares fund is up 15.5% so far this year.
For more information on low-volatility funds, visit our low-volatility category.
Max Chen contributed to this article.