JP Morgan has extended its lead at the top of the mergers and acquisitions league tables in Europe after advising Finnish mortgage lender OP-Pohjola Group on a $3.2 billion deal, meaning the US bank has now worked on four of the five biggest transactions involving European companies in 2014.

OP-Pohjola Group, Finland's biggest mortgage lender, has made an offer to acquire the remaining 44.62% stake in Pohjola Bank, its listed corporate banking arm, in a deal valued by Dealogic at $3.2 billion.