(10)For pre-marketing to be recognised as such under Directive 2011/61/EU, it should be addressed to potential professional investors and concern an investment idea or investment strategy in order to test their interest in an AIF or a compartment which is not yet established, or which is established, but not yet notified for marketing in accordance with that Directive. Accordingly, during the course of pre-marketing, it should not be possible for investors to subscribe to the units or shares of an AIF and the distribution of subscription forms or similar documents to potential professional investors, whether in draft or final form, should not be permitted. EU AIFMs should ensure that investors do not acquire units or shares in an AIF through pre-marketing and that investors contacted as part of pre-marketing can only acquire units or shares in that AIF through marketing permitted under Directive 2011/61/EU. Any subscription by professional investors, within 18 months of the EU AIFM having begun pre-marketing, to units or shares of an AIF referred to in the information provided in the context of pre-marketing, or of an AIF established as a result of the pre-marketing, should be considered to be the result of marketing and should be subject to the applicable notification procedures referred to in Directive 2011/61/EU. To ensure that national competent authorities can exercise control over pre-marketing in their Member State, an EU AIFM should send, within two weeks of having begun pre-marketing, an informal letter, in paper form or by electronic means, to the competent authorities of its home Member State, specifying inter alia in which Member States it is or has engaged in pre-marketing, the periods during which the pre-marketing is taking or has taken place and including, where relevant, a list of its AIFs and compartments of AIFs which are or were the subject of pre-marketing. The competent authorities of the home Member State of the EU AIFM should promptly inform the competent authorities of the Member States in which the EU AIFM is or has engaged in pre-marketing thereof.