SPI · methodology
Sneaker Price Index
SPI stands for Sneaker Price Index — an original index from SPI Markets. It's a simple score for how expensive popular sneakers are on the resale market compared with retail. 100 ≈ selling near retail. Above 100 means premiums; below 100 means sitting under retail.
Formula
price ÷ retail × 100
Each shoe's price-vs-retail is weighted by how much it's trading, then averaged into one number for the market.
Basket selection
ChronoPulse-style rules: up to 14 bestselling brands in the current top-seller pool, and up to 10 models per brand. Weights freeze until the next rebalance window (about every six months).
History
Boom-era tape (2020–2021) uses public Flurin17 research series. 2022–mid-2025 has no free daily public tape we trust, so that gap stays empty on purpose rather than inventing prints. Recent levels come from the live/snapshot basket when asks are available.
What it is not
- Not an official StockX index
- Not cleared sale prints — asks are marketplace quotes
- Not financial advice