The billionaire Lakshmi Mittal has pledged to invest $200m (£102m) in RAB Capital’s flagship hedge fund after the steel tycoon’s family holding companies agreed to buy £9m of new shares in the London money manager.

The Mittal family will increase its stake in Aim-listed RAB – founded by Philip Richards and Michael Alen-Buckley and named for their initials – from 5.4 to 6.2 per cent through a new share issue. It has also taken an option on a further 10m shares at £1 a share, above last night’s close of 98¾p, up ½p.