The dominance of financial centres such as London, New York and Tokyo in the $5 trillion-a-day global currency market may face challenges from landlocked cities as new technology erodes the advantage offered by high-speed undersea cables.
A European Central Bank research paper says these three centres, along with Singapore and Hong Kong, dominate the industry in part because of the history of submarine cables that have made high-frequency trading possible.
But, it says, new fibre optic networks that can also carry data at very high speed are being laid and which could influence the geography of the 24-hour, five-days-a-week currency market.
The location of foreign exchange hubs has implications for big trading firms and job creation as well as the prestige of the cities or countries in question.
There is also a political and policy edge to it now since the ECB has insisted all clearing and settlement of international euro currency trading must be conducted within the European Union - even if the world's biggest forex centre London were to find itself outside the bloc if Britain voted to leave the EU.
Were that to happen, the major centre for euro trade within the EU would probably be Frankfurt, the ECB's headquarters.
A 2013 survey of the FX market by the Bank for International Settlements showed that while the United Kingdom, the United States and Singapore expanded their share over the past decade, trading activity in Germany and Switzerland shrank. Between them, Germany and Switzerland account for just under 5 percent of global foreign exchange trade.
The ECB paper, however, says recently installed cables connecting landlocked cities have the potential to lure back high-frequency traders, who contribute about a third of trading.
It cited Spread Networks' cable between the data centres of the Chicago Mercantile Exchange and NASDAQ in New Jersey and euNetworks' fibre network route between Frankfurt and Zurich, a major centre for trade in the Swiss franc, the world's fifth most traded currency.
"Landlocked or not, there may be hope for Zurich after all," the paper concludes.
Toby Williams, head of euNetworks' ultra-low latency product, said there had already been a rise in high-frequency trading in foreign exchange but added the key driver was liquidity.
The first trans-Atlantic telegraph line was completed in the mid-1800s and was used to transmit the exchange rate between the dollar and the British pound. That gave rise to the trader slang for the currency pair - "Cable".
Sub-marine cable laying gathered pace in the late 1980s. Over time, their use for electronic trading of currencies and other financial instruments picked up.
But trading currencies needs more infrastructure.
Electronic trading platforms, such as those run by EBS and Thomson Reuters, on which most high-speed currency trading takes place, have to invest in expensive servers. High-speed trading firms prefer to be physically close to the servers to reduce transmission time.
The combination of high-speed cable connections and matching servers accounted for the growing weight of London and New York, said Barry Eichengreen, professor of economics at University of California, Berkeley, and co-author of the ECB paper.
Some veteran traders such as Alan Clarke who is global FX product manager at BBVA, say not all currency traders require access to the fastest technology.
"Aside from high-frequency types, non-speculative, real money flow isn't as sensitive to micro-second latency," he said.
Nonetheless, Brad Bailey, director at research and advisory firm Celent, which focuses on the impact of technology on financial services, said it was likely new cables would be a factor allowing other cities to gain market share.
"I expect over the next decade to see a change in the balance of where the FX centres are globally," he said.