Hellman & Friedman has turned to the debt markets to pay itself a dividend by refinancing oil and gas research company Wood Mackenzie, just one year after the US-based private equity firm bought the business.

Wood Mackenzie, which was bought from London-based buyout firm Charterhouse in July last year in a deal that valued the company at £1.1 billion, has added a £135 million loan to its debt structure to fund a dividend, according to three sources familiar with the situation.