Fees on exchange-traded funds continue to march downhill.

State Street Global Advisors announced early on Tuesday that it chopped management fees on nearly one-third of its SPDR ETF lineup. The cuts affect 41 of the firm's 145 US-listed offerings and include both domestic and international themed funds that own both stocks and bonds. Also included are a handful of so-called "smart beta" or "strategic beta" funds, which rank holdings by factors including momentum and low volatility. SSGA is the investment management arm of State Street.