First launched in 1985, reference 3940 replaced the existing perpetual calendar wristwatch, the reference 3450. Featuring a slender, circular-shaped case, the watch presented a decidedly more "modern" and less angular appearance than its predecessor. At the time of manufacture, it was amongst one of Patek Philippe's longest running references ever produced, ceasing production in approximately 2007. The reference was cased predominantly in yellow gold, as well as pink gold, white gold, and platinum.

The reference 3940 was executed in three different series (and a very small “pre-series”):

- Pre-series: 25 numbered Beyer pieces with gilt dial

- First series: without second case back, sunken sub dials, 24-hour counter two-tone

- Second series: with second back (all but platinum), sloped sub dials, 24-hour counter two-tone

- Third series: with second back (all but platinum), sloped sub dials, cross divider on leap year, 24-hour counter (The present example)

The present watch falls within the serial number range for the third series. Preserved in excellent condition with crisp hallmarks and a beautiful dial with a warm patina on the 24-hour subdial, the timepiece is further complete with its solid white gold caseback, setting pin and Certificate of Origin. One of the most collectible perpetual calendar in recent times, the 3940 in white gold will surely please any collector who enjoys the complication of a perpetual calendar yet with the convenience of a self-winding movement.