(4)The features of a crisis leading to significant cross-border financial market stress, or of a major regime shift, that materially affects institutions across the Union, are unique to every such crisis or regime shift. It would therefore not be appropriate to lay down in a prescriptive manner an exhaustive set of indicators that would be deemed to always adequately capture the nature and intensity of the financial market stress or major regime shift at hand. However, based on past experience, a significant increase of the level of volatility, changes in correlation levels, and the fact that the significant cross-border financial market stress or the major regime shift manifest themselves very quickly and suddenly should be considered common traits of non-ordinary situations. Still, a sudden increase of the level of volatility, or changes in volatility levels, on their own, may not be sufficient to characterise a situation as one of significant cross-border financial market stress or of a major regime shift and, therefore, should not automatically lead to the recognition of extraordinary circumstances as referred to in Article 325az(5) and Article 325bf(6) of Regulation (EU) No 575/2013.