Companies are using fewer advisers for mergers and acquisitions than at any point since 2001, as they look to cut costs amid the downturn and make greater use of in-house expertise.

The average number of advisers on European deals valued at more than $5 billion is 4.14 for the year to Aug. 7, compared with an average of 4.92 over the past five years, according to data from research provider Dealogic.

Adviser numbers globally have dropped from 4.34 to 3.81, while for U.S. transactions they are 3.67, down 8% from their five-year average.

Robert Leitao, head of UK M&A at Rothschild, said: "There have always been more advisers credited for advice than are actually working on deals or receiving fees for advice. This practice became particularly prevalent at the height of the market when banks would often receive advisory credit as a quid pro quo for providing financing or because they were the corporate broker."

Banks were previously rewarded with league table advisory credits in exchange for providing debt financing, despite having very additional little involvement in the transaction. Mittal Steel's $43.1 billion acquisition of peer Arcelor in 2006 marked one of the largest rosters of advisers, with 16 involved, the same number as French utility Suez's $58.7 billion acquisition of Gaz de France.