Reference 3940, the quintessential perpetual calendar and distinguished by its timeless elegance, is undeniably amongst Patek Philippe's greatest classics. Launched in 1984 as replacement for reference 3450, it was at the time the slimmest automatic perpetual calendar wristwatch.

An initial series of around 100 pieces were manufactured between 1984 and 1985, the first 25 were especially made for the 225th anniversary of Patek Philippe's retailer Chronometrie Beyer in Zurich, numbered and personalized. Starting in 1985, reference 3940 went into standard production until the model's discontinuation in 2007 when it was replaced by reference 5140.

The present example has been very well preserved with crisp hallmarks still apparent to the back of the lugs. Most notably, AM/PM indication at 9 o'clock has matured particularly well with the lower half of this subsidiary dial a darker brown color due to the aging process. To the best of our knowledge this watch has never before been offered in public.

Examples of reference 3940 are illustrated and described in Patek Philippe Museum - Patek Philippe Watches - Volume II, p. 300, and in Patek Philippe Wristwatches by Martin Huber & Alan Banbery, second edition, pp 292 - 294.