Erik Herzfeld, president of Thomas J. Herzfeld Advisors, says that investors are sacrificing returns for liquidity when they choose traditional mutual funds and ETFs instead of closed-end funds. The issue -- which arises due to the structures of the different fund types -- is a problem because most investors never even consider it; Herzfeld notes that most investors would be willing to trade liquidity -- to lock in for longer -- if it meant for better returns from fixed-income on long-term investments.