U.S. investors are beginning to hoard gold and gold-related ETFs as more grow wary of any potential setbacks in an extended bull market rally.

According to a recent World Gold Council research note, gold-backed ETF flows in September increased by 22.4 metric tons to 2,357 metric tons globally. North America made up the lion’s share of the increased demand, contributing to an added 36 metric tons of gold through funds listed in the region, whereas European investors yanked 12 metric tons worth of gold over the month and Asian funds lost 1.7 metric tons of gold.

Physically backed gold-related ETFs, such as the SPDR Gold Shares (NYSEArca: GLD), iShares Gold Trust (NYSEArca: IAU) and ETFS Physical Swiss Gold Shares (NYSEArca: SGOL) all track gold price movements and are backed by storing physical gold bullion in vaults. Consequently, as demand for the gold ETFs rise and investors funnel more money into the ETFs, the gold trusts would naturally have to increase their gold bullion stores to reflect the increased demand.

In September, the SPDR Gold Shares, which is backed by the World Gold Council, led flows, accounting for 60% of gross global inflows, while the iShares Gold Trust added 5.2% to its total assets under management.

Meanwhile, European outflows came as the euro currency weakened 80 basis points against the U>S. dollar over the month.

North American gold-backed funds are slowly catching up to European funds in global growth in 2017, but they still trail 38% to 47%. European demand for gold-backed ETFs has increased in a politically charged year with a number of contentious elections spattered throughout 2017. Many investors may have turned to safe-haven gold as a way to mitigate potential political risks in an year marked by rising nationalistic and anti-euro sentiment that could shake the markets.

Global gold-backed ETFs collectively accumulated 2,356 metric tons of gold as funds added 191.9 metric tons, or $7.5 billion worth, year-to-date, representing a 7.7% rise in global assets under management since 2016. European funds continued to lead inflows, making up for nearly 56% of all inflows year-to-date.

For full disclosure: Tom Lydon’s clients own shares of GLD

The opinions and forecasts expressed herein are solely those of Tom Lydon, and may not actually come to pass. Information on this site should not be used or construed as an offer to sell, a solicitation of an offer to buy, or a recommendation for any product.