London has for the first time raised the veil on the size of its centuries-old gold market.

The daily average of $36.9 billion in bullion moving in and out of London’s over-the-counter market is just shy of the amount traded in New York, a new data release Tuesday showed.

The London Bullion Market Association said its members — which include large banks such as HSBC HSBC, -0.16% and JPMorgan JPM, -0.08% and those who back the popularly traded SPDR Gold Shares ETF GLD, +0.37% with their holdings — traded 30.2 million ounces of gold a day during the past week, including spot transactions as well as swaps and forwards and other smaller loans and deposits. That compares to the 34 million ounces a day traded on New York’s Comex CME, +0.97% exchange.

Daily average turnover for silver in London, meanwhile, is $5.2 billion, or just over 359 million ounces.

The market has faced greater scrutiny and a louder cry for transparency as part of regulators’ efforts to contain risks following the 2008-2009 financial crisis. More trades from Zurich’s settlement hub are also being released.

“The publication of LBMA market data can only strengthen the integrity and improve the reputation and position of the global OTC market,” said Ruth Crowell, CEO of LBMA.

The association said it will publish the data daily starting in the first quarter of 2019. LBMA accounts for most but not all London trading activity and some members are just beginning to report volumes.

Contracted gold also trades on the London Metals Exchange. And, futures trading has long been a more accessible window on precious metals pricing, including intraday changes. Gold for December delivery US:GCZ8 on Comex put up its first loss in five sessions Tuesday, changing hands near $1,221.20 an ounce.