Accompanied by a Patek Philippe Extract from the Archives confirming production of the present watch in 2005 and its subsequent sale on July 27th of the same year.
Reference 3940 was launched in 1984 as a replacement for the reference 3450. The present watch is from the first series, featuring sunken subsidiary dials for the 24 hours display and leap year indicator, as opposed to the even version of later models. At its time it was heralded as the slimmest perpetual calendar wristwatch. An initial series of around 100 pieces were manufactured between 1984 and 1985, the first 25 were especially made for the 225nd 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 and three further series were produced.
The model is illustrated in Patek Philippe Wristwatches by M. Huber & A. Banbery, second edition, pp. 292-293.