Investment banks in the City of London have generated more than $10bn in fees so far this year, as a booming mergers and acquisitions market helps offset tumbling revenues from equity deals.

The value of M&A deals in Emea is up around 50% this year, according to figures from data provider Dealogic, with transactions such as German pharmaceuticals and chemicals giant Bayer's $66.3bn takeover of Monsanto among those to complete.