The top five investment banks stand to make margins of 15% to 20% in cash equities, but life will be "very difficult" for mid-tier firms with global ambitions, according to Morgan Stanley and Oliver Wyman, in a report which stresses the importance of market share in a highly competitive industry.

Unlike other areas such as foreign exchange, only the top five players and boutique firms in cash equities will be able to deliver margins of more than 10%, with mid-tier firms losing out, according to the report.