(17)The provisions governing transfers of portfolios should be in line with the single authorisation provided for in this Directive. They should apply to the various kinds of transfers of portfolios between reinsurance undertakings, such as transfers of portfolios resulting from mergers between reinsurance undertakings or other instruments of company law or transfers of portfolios of outstanding losses in run-off to another reinsurance undertaking. Moreover, the provisions governing transfers of portfolios should include provisions specifically concerning the transfer to another reinsurance undertaking of the portfolio of contracts concluded under the right of establishment or the freedom to provide services.