In his new role, van Leeuwen will be responsible for distributing the firm's ETF range to investors in Belgium, the Netherlands and Luxembourg.
He will report to Hector McNeil, co-founder and co-CEO of HANetf, who was recently named in ETF Stream's Industry 30 for the second year in a row.
van Leeuwen spent three years in his second stint at IMC before the firm made the decision to close its equities and ETF trading business in Europe last November.
During his first spell at IMC, he spent six years at the firm between 2008 and 2014, most recently as a senior trader.
He subsequently joined Source in October 2014 as an executive director in its capital markets business before re-joining IMC in 2017.
McNeil commented: "We are pleased to have Rick join the team as his in-depth experience in ETFs and trading will be an important component of our continued growth across Europe."
HANetf has made a number of appointments this year including Robert Dickson as director of sales for the UK and Ireland and Kilian Richter as assistant director of Nordic Sales and French-speaking Switzerland in May.
van Leeuwen's appointment is the latest sign HANetf is looking to expand its European footprint after registered six products in Austria and five in Switzerland in May.
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