Which is the most active pair in the London session, Tokyo session and New york session ?
According to the BIS study called Triennial Central Bank Survey, the dollar is on one side of 89% of all transactions, followed by the euro (37%), the yen (20%) and the pound sterling (17%). EURUSD is by far the most traded currency pair, with 28% of global turnover, followed by USDJPY with 17% and GBPUSD with 14%. (details: Foreign exchange market turnover by currency pair)
I dont think the distribution can change significantly from session to session.
In London the most active pair is GBP/USD, which is also somtimes called, the cable. It is prone to huge breakouts and dramatic reversals.
In Tokyo session it seems to be the USD/JPY which is most active at the opening of the Asian session (6 PM to 9 PM EST) as well as during the early US trading session (7 AM � 10 AM EST).
As for the New York session EUR/USDis most actively traded, but most of the action is concentrated in the time when the US and European banking hours overlap, from 7:00 AM EST to 10:00 AM EST. Of all the major pairs, this pair best reflects how the US economy is doing compared to the rest of the world.