The value of mergers and acquisitions deals in the US has fallen to its lowest level as a proportion of market capitalisation since the early 1980s, according to a report by Credit Suisse First Boston.

The same analysis of European volumes shows that they have fallen to their lowest levels as a proportion of market cap since 1986. The report underlines the extent of the slowdown in activity in the M&A markets, which has prompted thousands of redundancies at investment banks in the past few months.