Three big professional services firms – EY, KPMG and PwC – are stepping up their efforts to snatch a slice of the M&A market from investment banks – by hiring the banks’ own talent.

All three firms have made notable appointments in London in recent weeks and more are expected. Banks are already under pressure on big-ticket deals from boutiques set up by veteran dealmakers. The accountants are now trying to take banks' share of mid-sized and smaller deals.