The permitted percentage of sale or purchase shall be calculated in two periods throughout the calendar year: 1. The period from 1 January to 30 June. 2. The period from 1 July to 31 December. The permitted percentage of sale or purchase shall be calculated based on the total ownership of the Controller at the beginning of these periods. This percentage shall also include any sale or purchase, whether directly or indirectly, by the Subsidiary Companies or persons with whom they are Acting in Concert with it.