Silver exchange traded funds (ETFs) are shining ever brighter as silver prices are pushing towards $40 an ounce.

Silver is the top-performing precious metal so far this year with a 29% rise to 31-year highs, Reuters reports.

Back in 1973, the Hunt family bought precious metals to hedge against inflation, but since gold couldn’t be held by private citizens at the time, the Hunts hoarded silver instead, writes Brian Trumbore for Buy and Hold. Nelson Bunker Hunt and William Herbert Hunt, along with other wealthy individuals, created a silver pool. After a short period, they controlled more than 200 million ounces of silver, or half the world’s deliverable supply. When the brothers began their scheme, silver prices were around $1.95 per ounce, but by the early 1980s, prices were in the $50 range, peaking at $54.

iShares Silver Trust (NYSEArca: SLV)