Reference 5235 was released at Baselworld fair in 2012. The uniqueness of this watch lies in its movement which is constructed with caliber 31-260 REG QA, the last letters standing for Régulateur Quantième Annuel. This is the first ever modern Patek Philippe annual calendar wristwatch produced with a regulator dial.

In horological history, a regulator was a centrally located clock found in watchmaker workshops, with the large minute hand taking up visual importance. This allowed the watchmakers to regulate the watches that they were building against the time displayed on the central regulator, hence the name. The regulator dial allows for more accuracy than a normal watch because it has non-coaxial hour and minute hands, meaning, the hour and minute hands do not share the central pinion position on the dial but are independently placed. This reference is considered among collectors to be one of the most significant technical innovations in Patek Philippe's history.