The deal is unlikely to impact its merger with Deutsche Boerse as most of the regulatory scrutiny around the $28 billion deal is focussed on the combined entity's large footprint in clearing, derivatives and index licensing businesses.

Mergent would become part of the UK firm's information services division, adding data on 250 million public and private companies to LSE Group's basket.

LSE Group did not disclose the terms of the Mergent deal, which is expected to close by Jan. 31.

The exchange operator's information services unit accounted for over 36 percent of 2015 revenue from continuing operations.

LSE Group, which also owns Borsa Italiana, saw strong business in its latest quarter as the London stock market hit record high levels and benefited from a slide in the pound since Britain's June 23 vote to leave the European Union.

Lazard Middle Market acted as financial advisor to Mergent, while Sagent Advisors advised the LSE.

Shares in LSEG, Europe's oldest independent bourse, were down 1.7 percent to 2825p at 1438 GMT.

(Reporting by Rahul B in Bengaluru; Editing by Anil D'Silva)