The consequences of the Brexit vote will be felt throughout the legal systems, both in the UK and in the EU. The legal consequences of the Brexit decision and the process which will lead to the withdrawal of the UK, raises numerous questions many of which are in the process of being analysed, and possibly solved. In the field of company law, with respect to cross-border matters, UK companies will be exposed to national laws in the EU States after the Treaty freedom of establishment will not further apply. This may lead to tensions between the two systems of recognition of foreign companies, i,e. the incorporation theory and the seat theory. Foreign companies active in seat jurisdictions may in the future be disqualified if their seat is effectively established in the seat State. Access may become more difficult, not on the basis of company law, but of sectoral regulations. In other part of the regulatory system, such as the rules on cross-border mergers, on rights of shareholders in listed companies, or disclosures to be made, equivalence of rules, as decided by the European Commission, will be the key factor. Additional issues will arise for the cross-border recognition of accounting standards and for the activity of auditors.