Collateralized loan obligations may become the next big push in the exchange-traded fund industry. VettaFi's Todd Rosenbluth suggests there's investor demand for the alternative assets due to ongoing interest rate uncertainty. CLOs are short-term fixed income strategies that consist of pools of floating-rate secured loans. "We've seen fixed income ETF demand be quite strong," Rosenbluth said. Last month's Fed's decision to keep rates unchanged is a catalyst for short-term product demand, according to Rosenbluth.