Swedish private equity firm EQT Partners has sold a portfolio company to its biggest investor in an unusual deal that raises questions about corporate governance in the buyout market. The transaction has come as more large investors are expected to source direct deals from their private equity managers.

EQT has sold healthcare company Aleris to Investor, a SEK152bn (€16bn) fund managed by Sweden's Wallenberg family, for about €470m ($588m) following an auction, according to a statement.