The BrickCheck™ Minifig Market Index (MMi) tracks secondary market appreciation for collectible LEGO® minifigures using a fixed-basket price index — the same methodology used in national Consumer Price Index (CPI) calculations.
The index answers a single economic question: If you had bought the same basket of minifigures at the market's base period prices, how much would that basket cost at today's prices? The answer, expressed as an index level, measures collective market appreciation.
Data is sourced exclusively from BrickLink, the largest LEGO secondary market, via the BrickLink API. Prices reflect completed used-condition transactions — actual sale prices, not asking prices.
BrickCheck MMi uses a fixed-weight (Laspeyres-type) price index. The basket composition and weights are fixed at the base period and held constant until annual rebase.
In plain terms: price the exact same basket of minifigures at today's prices vs. the base-period prices. A reading of 161 means that basket costs 61% more than it did in March 2026.
The BrickCheck FMV price is a proprietary composite displayed on fig cards and used for appraisal purposes. It blends completed sale prices with current market depth — and is not the index price input, which uses completed transaction prices only.
Every Liquid 300 constituent must pass all 5 gates simultaneously. Gate evaluation runs after every monthly scrape. Failure on any single gate triggers removal review.
Total universe: 18,740 minifigures tracked across the BrickLink catalog.
Liquid 300: 300 — selected by liquidity rank (most-traded figs passing all 5 gates).
Top 700 pool: The waiting list of gate-eligible candidates monitored monthly.
Data source: BrickLink secondary market API (two-account rotation).
Scrape cadence: Monthly on the 16th at 09:00 UTC.
Annual rebase: Every March — basket reviewed, chain factor updated, period index reset to 100.
Permanently excluded: Friends, DUPLO, and Jack Stone themes. Event-exclusive and convention-only figures (Toy Fair, SDCC, Comic Con) are retained — their replacement values serve appraisal purposes.
Each theme subset runs its own Laspeyres calculation monthly. Themes are derived automatically via GROUP BY — never hardcoded. Star Wars is split into Classic (pre-2013) and Modern (2013+) eras.
Each minifigure in the BrickCheck universe receives a MMi Score — a proprietary composite intelligence score on a 1–99 scale. The score is designed to surface which figures have the strongest combination of market liquidity, price appreciation, scarcity, and collector demand.
The MMi Score is computed using a three-dimension architecture: Liquidity, Replacement Value, and Investability. Each dimension is scored independently and combined via geometric mean — rewarding well-rounded figures over those dominant in a single dimension.
Constituents are monitored monthly under a three-tier framework: immediate mid-period removal for market collapse or data failure, annual rebase review for slow-moving quality and liquidity signals, and ongoing watch-list monitoring for borderline cases. The framework prioritizes index integrity — no constituent remains in the basket if market data ceases to support it.
Base period: March 25, 2026 · Index = 100
First reading: March 2026 (inception)
Latest reading: —
Monthly scrape: 16th of every month, 09:00 UTC
Annual rebase: Every March — basket reviewed, additions/removals published 2 weeks prior
Historical series: Never revised. Chain-linking preserves continuity through rebases.
Data provider: BrickLink (bricklink.com) — largest LEGO secondary marketplace
