1. An auction platform shall conduct auctions separately through its own regularly recurring bidding window. The bidding window shall be opened and closed on the same trading day. The bidding window shall be kept open for no less than two hours. The bidding windows of any two or more auction platforms may not overlap and there shall be at least a two-hour delay between two consecutive bidding windows.
2. The auction platform shall determine the dates and times of the auctions taking account of public holidays that affect international financial markets and any other relevant events or circumstances that, in view of the auction platform, might affect the proper conduct of the auctions necessitating changes. No auctions shall be held in the two weeks over Christmas and New Year of each year.
3. In exceptional circumstances, any auction platform may, after consulting the auction monitor and obtaining its opinion thereon, change the times of any bidding window, by giving notice to all persons likely to be affected. The auction platform concerned shall take the utmost account of the auction monitor's opinion.
4. As from the sixth auction or earlier, the auction platform appointed pursuant to Article 26(1) or (2) shall conduct auctions of allowances covered by Chapter III of Directive 2003/87/EC on a weekly basis at least and auctions of allowances covered by Chapter II of Directive 2003/87/EC shall be conducted on a two-monthly basis at least.
No other auction platform shall conduct an auction on any of a maximum of two days a week during which an auction platform appointed pursuant to Article 26(1) or (2) conducts an auction. Where the auction platform appointed pursuant to Article 26(1) or (2) conducts auctions on more than two days a week, it shall determine and publish on which two days no other auctions may take place. It shall do so no later than when it makes the determination and publication referred to in Article 11(1).
5. As from the sixth auction or earlier, the volume of allowances to be auctioned on the auction platform appointed pursuant to Article 26(1) or (2) shall be distributed evenly over the auctions held in a given year, except that volumes auctioned in auctions held in August of each year shall be half of the volume auctioned in auctions held in other months of the year.
6. Additional provisions on the timing and frequency of the auctions conducted by any auction platform other than the auction platforms appointed pursuant to Article 26(1) and (2) are set out in Article 32.