In Chapter 4, an examination is conducted to establish whether PCOs are included in preferential trade agreements (PTAs) and to identify common patterns as well as the different typologies of provisions that have emerged over the last twenty years. It is noted that the model set up in the GATS is still the most commonly adopted in trade negotiations. It is also shown that Members, when they really want to ‘lock in’ their trade commitments and ensure the PCO is narrowly interpreted or only available upon satisfaction of one or more requirements (be it a necessity test or a non-discriminatory application of prudential measures), have the necessary tools to do so. It is emphasised that this happens only in a minority of cases, given that the overwhelming majority of preferential PCOs give parties substantial leeway when they regulate financial markets according to prudential concerns. Finally, recent developments in current negotiations are examined.