Back in mid-July, the iShares Edge MSCI Minimum Volatility USA ETF (USMV) - Get Report was up over 12% for the year, more than double the return of the S&P 500 at the time. Fast forward to last Friday and the USMV is only up 5% year-to-date, only a percentage point ahead of the index. Don't put too much weight into the USMV's second half selloff, it was trading ahead of itself early in the year anyway, said Robert Nestor, managing director and Head of iShares Smart Beta Strategy at BlackRock. In his view, the recent move towards momentum stocks reflects an increasing desire by investors to outperform and move away from the defensive stocks which led the market through July. Two other smart-beta ETFs gaining a lot of attention, according to Nestor, are the iShares Edge MSCI Multifactor USA ETF (LRGF) - Get Report , up 4% year-to-date, and the iShares Edge US Fixed Income Balanced Risk ETF (FIBR) - Get Report , which is up 6.6% thus far in 2016. The LRGF is the "reciprocal" of the USMV, according to Nestor, because it is designed to outperform as opposed to limit risk. Meanwhile, the FIBR's goal is to balance out duration and credit risk.