The London bullion market has seen intermittent shortages of 400-ounce bars, traders in the City told FastMarkets, pushing premiums for physical delivery for these large bars as high as 50 cents.
This shortage may have been driven by several factors, including a scramble for physical delivered material after the end of the year and reduced availability due to good delivery bars flowing from London to the Far East, they suggested.
“There is a shortage of big bars, especially good-delivery 400-ounce bars,” Bernard Dahdah at Natixis said. “One part of the problem is that large quantities of these bars that have come from ETFs, have now been moved to be re-refined into three-nines bars of smaller sizes and are therefore no longer available to the London market.”
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http://www.fastmarkets.com/gold-news/69679-0-en
Note that the shortage is in bars that meet the 400ozt good trading size specification. They apparently have other sized bars.