From above link, no idea this market existed.

Considered among the most complicated mechanical watches ever produced, the Patek Philippe Henry Graves Supercomplication became the world's most expensive timepiece when it sold for 23.2 million Swiss francs ($24 million) in 2014. That record was comprehensively smashed five years later by an unworn Patek Philippe Grandmaster Chime 6300A-010, created especially for a charity auction in Geneva, that fetched 31 million Swiss francs ($31.2 million)