The European Commission said on Monday it has opened an in-depth investigation to assess the proposed $27 billion acquisition of Refinitiv by the London Stock Exchange Group (LSEG) under the EU Merger Regulation.

The Commission highlighted potential problems ranging from the companies’ combined control of financial data and the effect the deal could have on trading and clearing of bonds and derivatives.

“The Commission is concerned that the proposed acquisition may reduce competition in trading and clearing of various financial instruments and in financial data products,” said the Commission in a statement.

The European Commission set an October 27 deadline for its decision.

Refinitiv is 45%-owned by Thomson Reuters.

Commission executive vice-president Margrethe Vestager, responsible for competition policy, said: “Financial markets provide an essential function for the European economy.

“Access to financial market infrastructure and financial data products is needed to make investment decisions, trade, and to protect savings.

“We have opened an in-depth investigation to assess whether the proposed transaction which will combine the activities of LSEG and Refinitiv would negatively affect competition in these markets.

“It is key for a well functioning financial market to ensure that market participants continue to have access to financial market infrastructure and financial data products on competitive terms.”