This year's ambitious overhaul of the rules governing the European Union's financial services industry will catch many companies unprepared, with one new poll suggesting that only four in 10 financial firms will be ready when the new regime comes into effect eight months from now.

Concern over the shake-up associated with the EU's markets in financial instruments directive (Mifid) has been rising for months. The controversial legislation is intended to create an open, competitive, cross-border market for financial services.

It will allow companies to market products across 27 member states under a single set of harmonised rules, and will force stock exchanges to compete with investment banks for parts of their business.

Acknowledged as the EU's most ambitious attempt to realise a deep and liquid cross-border financial market, Mifid has been criticised by the industry and some regulators who fear compliance costs will not be offset by efficiency gains.

Increasingly, that concern is being overshadowed by fears that thousands of financial services companies will fail to meet Mifid's complex requirements by November, when it takes effect.

Big banks and financial service groups are expected to be prepared, but the directive also affects a large number of smaller firms, such as regional stockbrokers and investment advisers.

The poll, sponsored by business software group Handysoft, found that almost two-thirds of financial firms expected "not to be compliant", while more than one-third of the firms had no dedicated Mifid compliance officer to oversee the transition to the new regime.