9. VanEck Vectors Gold Miners  GDX  -22.09%

Gold miners did poorly despite gold’s reputation as an inflation hedge. GDX is the first gold miner’s ETF on our list, and it lost 21.1% over a one-year period ending on Sept. 16. To some extent, gold’s strong performance over the first few months of the year has made its decline since mid-spring even more pronounced.