He spoke at Monday's Reuters Global FX Summit in New York.

Analysts said global FX reserves have been steadily weakening since May.

But the topline increase in daily global FX turnover hides growing headwinds facing the industry.

London and New York hold the first and second spots in market share in global FX trading.

At the end of 2007, global FX reserves stood at $6.7 trillion.

Salvatore Rubino has taken over from Billington as head of global FX derivatives trading and will report to him.

As a result, carry trading has returned 5.5 percent in 2019, according to HSBC's Global FX Carry Index.

Record Currency Management CEO James Wood-Collins speaks during the Reuters Global FX Summit in London April 22, 2013.

Record Currency Management CEO James Woods-Collins speaks during the Reuters Global FX Summit in London April 22, 2013.

Having built my career in the global FX banknote industry, I am a great advocate of cash and always keep some in my wallet.

Deutsche Bank, Citigroup, UBS and Barclays are the four biggest players in the global FX market with a combined share of over 50 percent.

But there's reason to believe that the dollar's long reign as global FX reserve king may be more vulnerable now than it has for decades.

New data in the 2013 survey also showed 16 percent of dealers' global FX transactions were conducted by a prime brokerage.

London is the hub of the global FX market, accounting for around 40 percent of its $5.3 trillion-a-day turnover.

Deutsche Bank Global Head of Foreign Exchange Kevin Rodgers speaks during the Reuters Global FX Summit in London April 22, 2013.

Last year, Britain's Financial Conduct Authority began a formal investigation into possible manipulation in the $5.3 trillion-a-day global FX market.