As the biggest investment in Mainstream, the deal means that Marubeni is now the the Irish developer's largest institutional investor, holding a 25% stake in the firm and gaining representation on the board.
According to the Japanese company, Mainstream's involvement in emerging markets such as Chile and South Africa helped seal the deal. It added it was particularly looking at pre-consent projects with the aim of understanding the industry
It also extends Marubeni's involvement in the wind sector — the company already owns significant shares in the Gunfleet Sands offshore project in the UK and the Raleigh wind farm in Ontario, Canada as well as heading a consortium planning to install floating turbines off of the Japanese coast.
Marubeni is not the first financial house to be tempted by Mainstream's involvement in emerging markets. In June, the developer signed a $1.4 billion joint venture deal with private equity company Actis to develop 600MW of renewables projects.