Holdings topped late 2012 levels, at which time the gold price was near $1700/oz, about 18% higher than current levels, the council said.
North American and European-listed funds now make up 52% and 44% of the global holdings, respectively, with the remainder coming from funds in Asia and other regions.
This was "vastly different" to the gold-backed ETF landscape in 2012, the council said, when two-thirds of global holdings were concentrated in North America. During September, North American funds led global flows by adding 62.1t or 83% of net inflows.
Low-cost gold-backed ETFs continue to grow, adding 2.9 t during the month to bring total holdings to 61t, worth some $2.9 billion.
European-listed funds brought in 7.7t, mainly in the UK, as investors positioned for the impending Brexit decision expected by October 31.
Funds in Asia also had another month of strong inflows at 3.9t, mainly driven by Chinese funds.
The council said the gold price rally has paused on the back of rising global rates and US dollar strength, falling by 3% in dollar terms in September after rising by 20% during the previous four months.
Global demand for gold-backed ETFs remained strong, the WGC said, especially since gold remained near all-time highs in every major Group of 10 currency, except the US dollar and Swiss franc.
Positive sentiment towards gold was also reflected in Comex net longs, which reached all-time highs equivalent to 1,134t during the month. This volatility skew in the options market was at an all-time high, measured against available data from 2007 onwards, the WGC noted.
The skew, it explained, was computed as the difference in premia paid between puts and calls at equivalent strikes, implying market participants were willing to pay a significant premium for exposure to a higher gold price versus protection against a lower price.
The council highlighted gold price performance was likely to be impacted by uncertainty around monetary policy direction, but several potential positive catalysts could support a higher price in October.
First, global uncertainty continues, considering the US House of Representatives initiated a preliminary inquiry as to whether to proceed with a formal impeachment investigation of president Donald Trump. This move, the council explained, could negatively impact on risky assets and drive China to potentially delay trade solutions until the 2020 presidential election.
Additionally, there is still uncertainty until the deadline for a Brexit decision or another deadline extension.
Second, despite the increases during September, interest rates globally remain low. The council estimates that more than 80% of sovereign debt is trading with negative real rates, which lowers the opportunity cost of investing in gold.
Lastly, the US stock market was trading near all-time highs and, historically, October was a month when some of the sharpest historical down-moves in stock performance were seen, the WGC pointed out.
Conversely, continued dollar strength and a deceleration in gold consumer demand in India and China could create potential headwinds.