According to Jim Steel, head of commodities strategy at HSBC, the SNB currently holds about 7.8 percent of its reserves in gold and that would require massive purchases. So far it seems unlikely to pass, but if sentiment changes and it looks like it would be approved, gold could quickly gain $50.
"The polls so far indicate it will not pass," he said. "The market has given the impression that it does not believe it would pass." The referendum was proposed by the ultraconservative Swiss People's Party.
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Bart Melek, head of commodities strategy at TD Securities, calculated that if the referendum did pass the SNB would have to buy about 1,800 tons of new gold—or 350 tons a year over the next five years to make up 20 percent of the $541 billion reserves.
"It could certainly act as a stabilizing factor," he said, but added it's unlikely to become law. "There's a pretty large impediment to that becoming legislation. You've got the government against it, the Swiss National Bank against it."
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Another central bank story that is likely to become more real is the speculation that Russia's central bank will have to begin selling gold, he said.
"They are burning through reserves massively, $10 billion a week. Their gold holdings are close to 10 percent and maybe 11 percent. As they burn through reserves, gold becomes a disproportionately large part of reserves," Melek said.
Russia selling gold from its reserves is more likely than a referendum forcing the Swiss National Bank to buy it, he said.
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Gold is down 2.5 percent so far this week, and Steel said it appears to be stabilizing. The December futures contract was fluctuating between positive and negative territory just around $1,145 per ounce.