By Jack Ryan and Yihui Xie

(Bloomberg) -- Gold traders faced a volatile session on Friday as a technical outage on the Chicago Mercantile Exchange disrupted markets, bringing another headache just weeks after the longest-ever US government shutdown ended.

The hours of disruption hit trading across markets including gold futures and options on the Comex, which are often used to hedge exposure to prices in London. A lack of live trading or pricing for those contacts can make it harder to trade as they diverge from spot prices in London, the dominant trading hub.

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Spot bullion rose as much as 0.9%, before paring gains in choppy trading as the issue took hold, with the market also seeing a brief surge in bid-ask spreads. The outage comes after traders had also recently faced the challenge of the US government shutdown, which had affected the release of economic data that markets use to gauge the outlook for US interest rates.

“Spot and futures market goes hand-in-hand, as bullion traders use the futures to offset or hedge activity in the spot market,” said Saxo Bank A/S strategist Ole Hansen. “When that leg goes dark, the spot market suffers as well through higher spreads and lower activity, obviously not helped by the fact this was going to be a quiet day anyway, with the long Thanksgiving weekend in the US.”

With Comex contracts affected, some traders said they reverted to old-school methods of calling brokers and dealers by phone on Friday in order to hedge their exposures. EBS, a popular electronic platform used for foreign-exchange and precious-metals trading, was also impacted by the CME outage.

Bid-ask spreads, the gap between what dealers offer to pay for gold and what they will sell it for, briefly surged to well above $20 an ounce, before falling back. These spreads, which are typically about $1 an ounce, tend to widen when there is less liquidity in the market, or during periods of extreme volatility.

Meanwhile, bullion is still up more than 2% this week, and on track for its fourth monthly gain after hitting a record high in October. A series of comments by Federal Reserve officials and the release of delayed economic data have supported the case for lower borrowing costs, which typically benefit gold as it doesn’t pay interest.