1. Subject to Article 22, a competent authority may take one or more of the measures referred to in paragraph 2 of this Article where:

(a) there are adverse events or developments which constitute a serious threat to financial stability or to market confidence in the Member State concerned or in one or more other Member States; and

(b) the measure is necessary to address the threat and will not have a detrimental effect on the efficiency of financial markets which is disproportionate to its benefits.

2. A competent authority may prohibit or impose conditions relating to natural or legal persons entering into:

(a) a short sale; or

(b) a transaction other than a short sale which creates, or relates to, a financial instrument and the effect or one of the effects of that transaction is to confer a financial advantage on the natural or legal person in the event of a decrease in the price or value of another financial instrument.