'ETFs That Have Never Been Seen Before in the ETF Universe'

Nontransparent ETFs are coming, the only question is when, said Ed Rosenberg, head of ETFs for American Century Investments, at the Inside ETFs Conference. 

Rosenberg said he expects American Century to be first to market with nontransparent ETFs, most likely during the first quarter of the year, followed by Precidian Investments' partnership with Legg Mason. 

He said American Century has legal filings in with the Securities and Exchange Commission that are still awaiting approval. 

When approved, however, they will bring "ETFs that have never been seen before in the ETF universe," Rosenberg said.