Article 6 of the Act no 4054 prohibits abuse by one or more undertakings of their dominant position in a market for goods or services. This provision prohibits the use by one or more undertakings, which have power to determine economic parameters such as price, supply and distribution amount, of this power to restrict competition, thus, in a way contrary to fair competition. The aim is to prevent monopolization created by anticompetitive conduct in markets. 

As understood from the wording of article 6 of the Act no 4054, the Act does not prohibit being or becoming dominant but abusing dominant position to restrict competition. Therefore, it is critical to determine dominant position for the enforcement of the article.  For the determination of dominant position, factors such as market share, barriers to entry, vertical integration and product substitutability are taken into account. The assessment considers whether the undertaking (or undertakings) acts independently of its competitors and customers, which is provided for dominant position in the Act no 4054.

Some examples related to abusive cases are listed in Article 6 of the Act no 4054. Accordingly, the article lists abuse of dominant position cases as follows: complicating the activities of competitors in the market, preventing undertakings from entering  the market, offering different terms to purchasers with equal status, tying the purchase of a good or a service with the condition of purchasing another good or service. However, abusive conducts are not limited to the examples listed in the article. For instance, applying excessive sale prices may be regarded as abuse of dominant position.

Guidelines on the Assessment of Exclusionary Abusive Conduct by Dominant Undertakings is given below.

Guidelines on the Assessment of Exclusionary Abusive Conduct by Dominant Undertakings - Date of Adoption: 29.01.2014 Decision Number:  14- 05/ 05- RM(1)