With traders pricing in near certainty that U.S. borrowing costs will rise next month, silver investors are heading for the exit.

This month through Thursday, almost $79 million was pulled from iShares Silver Trust, the largest exchange-traded fund backed by the metal. That would be the biggest monthly outflow since January. Holdings in all silver-backed ETF tracked by Bloomberg worldwide fell by 2.9 million ounces, set for the first monthly decline in 10 months.