The Luxury Watch Index employs a systematic, rules-based methodology to track price movements across ten of the most liquid and widely traded references in the secondary luxury watch market. Each week, the ten lowest Ask prices for each constituent watch were sourced from Chrono24, the world's largest online marketplace for luxury timepieces, providing a consistent and reproducible data set. The median of these ten prices was calculated as the representative weekly price for each reference, mitigating the influence of outlier listings and ensuring statistical robustness. Each constituent was then normalised against its base price recorded on 28 November 2025, converting absolute prices into a standardised index of relative performance. The composite index value is derived by calculating the equally-weighted average of all ten normalised constituent values, providing a single quantitative measure of aggregate secondary market performance. It should be noted that index constituents are priced on an Ask basis rather than confirmed transaction prices, which is consistent with standard practice across publicly available secondary watch market indices.