Entrepreneur Adam Mosseri spotted wearing a Audemars Piguet

Instagram head Adam Mosseri recently revealed a vintage Audemars Piguet ref. 5564PT perpetual calendar in platinum, one of the most technically accomplished and historically significant skeletonized watches produced during the final decades of mechanical watchmaking's commercial expansion. Photographed on the wrist in a candid indoor setting, this compact yet imposing timepiece exemplifies the Swiss manufacture's engineering philosophy during a critical period in its legacy.

The ref. 5564PT is fundamentally a platinum variant of the openworked ref. 5568, itself an integrated-bracelet evolution of the ref. 5561. The case measures 36mm in diameter and just 7mm in thickness, crafted entirely in platinum and crowned by a distinctive stepped bezel adorned with a nautical-rope motif that simultaneously functions as hour markers. This dodecagonal aesthetic distinguishes the 5564PT from its less ornate siblings. The dial presents a deep blue chapter ring and registers that frame the perpetual calendar complication—month, date, leap-year indicator, and a moonphase display rendered in contrasting grey against the skeletonized movement visible beneath. The integrated platinum bracelet exhibits the same horizontal ribbed pattern as the bezel, creating visual cohesion throughout the design.

At the movement's heart beats the caliber 2120/2800SQ, an ultra-thin automatic movement developed by Audemars Piguet and based on foundational work by Jaeger-LeCoultre's legendary cal. 920. Designed by Jacqueline Dimier, one of horology's most influential female engineers, this movement carries historical weight beyond its technical specifications. In the late 1970s, when mechanical perpetual calendars had largely vanished from commercial production, this caliber—and the ref. 5548 family it powered—became a pivotal statement of AP's commitment to traditional watchmaking. The openworked dial reveals the intricate cam-work and jeweled components that execute the perpetual calendar function, demonstrating manufacturing precision at a scale few manufacture could achieve.

The ref. 5564PT occupies a narrow and exclusive niche within the perpetual calendar market. Production numbers remain undisclosed but are widely believed to be under 200 pieces across all variants of the ref. 5548 family. Platinum examples are rarer still, making Mosseri's vintage specimen a collector's trophy. Audemars Piguet only retired this movement architecture with the recent release of the ref. 26585XT—a 150-piece limited edition honoring the manufacture's sesquicentennial—confirming that the 2120/2800SQ lineage defined an entire era of AP horology.

On the grey market, vintage ref. 5564PT examples command prices ranging from $55,000 to $85,000 USD depending on condition, service history, and provenance. Original retail pricing for this reference in the 1980s exceeded $30,000, making it one of AP's most expensive watches of that decade. Today, demand from perpetual calendar specialists and platinum-watch collectors ensures sustained appreciation, with waiting lists common among dealers holding examples in excellent condition.