Natixis asset management unit H2O AM LLP helped German businessman Lars Windhorst settle a €66 million lawsuit from Romanello at the end of 2017, the Financial Times reported,
Romanello had links to Igor Yusufov, who was the energy minister during Vladimir Putin's first term as the Russian president, five people familiar with the matter told the FT.
A Belize-registered investment vehicle, Romanello had accused Windhorst of not honoring a number of trades of illiquid stock and bonds.
Investors in June withdrew funds from H2O on concerns over its holdings in illiquid bonds of businesses backed by Windhorst.