The sale for an undisclosed sum follows recent mega deals in the financial data and information sector, including S&P Global buying IHS Markit for $44 billion (33.03 billion pounds) and London Stock Exchange Group Plc's $27-billion acquisition of Refinitiv.

"Our deep expertise on energy markets will add to Medley's macro (economic) and policy offering and our plans to invest in Medley will further strengthen coverage and service for its clients," said Energy Aspects Chief Executive Fredrik Fosse.

(Reporting by Dmitry Zhdannikov, writing by Shadia Nasralla; editing by Emelia Sithole-Matarise)