A doubling of the amount of money spent on buyouts in the US in the first half of 2013 compared with a year ago is giving cause for optimism that a corner has been turned in the global private equity markets.

An uptick led by US activity drove the cumulative value of global private equity transactions to $121bn as of June, compared with $69.5bn in the first six months of 2012. It is the strongest first half of a year since 2008.