Goldman Sachs and Morgan Stanley have earned the most from mergers and acquisitions advice so far this year but it is UK bank Barclays that has shown the biggest improvement, entering the top-five revenue rankings for the first time.

The total value of global M&A deals reached $1.7 trillion over the year to the end of September, down 16% over the same time period in 2011, according to data from Thomson Reuters and Freeman Consulting. Volatile markets, weak investor sentiment and the continuing eurozone crisis has kept many deals off the table over the first nine months of the year.