"Actively managed" and fixed income are the themes for the top new ETF asset gatherers this year. Leading the way is the SPDR Blackstone/GSO Senior Loan Fund (SRLN) - 2 months old and with $279M AUM. There's very little duration risk since yields on senior loans rise alongside interest rates. Number two is the Barclays Select MLP ETN (ATMP) with $136.5M AUM. Rounding out the top 7: IBCC, MINC, FPE, SYLD, VWOB.