Alan Parker’s City agency was top of Mergermarket's global, European and UK league tables.
Globally Brunswick worked on 75 deals worth a combined US$117bn (£77bn). Following Brunswick in the global league table were Sard Verbinnen & Co with 47 deals and Joele Frank Wilkinson Brimmer Katcher with 27 deals worth US$72bn and US$68bn respectively.
The largest deal during the period was the US$28bn Brunswick-supported bid of Berkshire Hathaway and 3G Capital Partners for HJ Heinz Company.
FTI Consulting topped the global table in terms of deal volume, working on 94 deals worth US$44bn during the first half.
M&A volumes picked up towards the end of Q2, with the second quarter up 10.6 per cent from Q1, but H1 was still down 12.2 per cent compared to last year with deals valued at US$899.1bn from US$1,024.2bn the same time last year.
Brunswick topped the European table ahead of Hering Schuppener Consulting and FTI Consulting, and headed the UK table.
The UK table is notable for a number of traditionally smaller players in the financial PR market making up the top 10.
Second by deal value is Tavistock Communications (60th in the first half of 2012), followed by Powerscourt and Hering Schuppener Consulting.
Also making the top 10 were StockWell Communications, Greenbrook Communications and Publicis-owned CNC.
UK financial PR heavyweights RLM Finsbury came 13th, working on 18 deals worth US$3.1bn (92 per cent down year-on-year), while Tulchan Communications came 15th with 16 transactions worth US$2.2bn.