1. Where this Directive requires national regulatory authorities to determine whether undertakings have significant market power in accordance with the procedure referred to in Article 67, paragraph 2 of this Article shall apply.

2. An undertaking shall be deemed to have significant market power if, either individually or jointly with others, it enjoys a position equivalent to dominance, namely a position of economic strength affording it the power to behave to an appreciable extent independently of competitors, customers and ultimately consumers.

In particular, national regulatory authorities shall, when assessing whether two or more undertakings are in a joint dominant position in a market, act in accordance with Union law and take into the utmost account the guidelines on market analysis and the assessment of significant market power published by the Commission pursuant to Article 64.

3. Where an undertaking has significant market power on a specific market, it may also be designated as having significant market power on a closely related market, where the links between the two markets allow the market power held on the specific market to be leveraged into the closely related market, thereby strengthening the market power of the undertaking. Consequently, remedies aiming to prevent such leverage may be applied in the closely related market pursuant to Articles 69, 70, 71 and 74.