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.
P(t,i) — Current period price: the 6-month average of completed used-condition sale prices from BrickLink for fig i at time t.
P(base,i) — Base period price: the used-condition average at March 2026. Locked permanently — never revised.
Q(base,i) — Base period quantity weight: combined new + used historical transaction volume at March 2026. Locked permanently — never revised.
A NULL current price (fig temporarily inactive) contributes zero to the numerator and its full base weight to the denominator — a deliberate conservative bias.
The BrickCheck FMV price is a proprietary composite displayed on fig cards and used for appraisal purposes. It is not the index price input — the index uses completed transaction prices only.
Used Avg — 6-month average of completed used-condition BrickLink sales. Economic ground truth for the index.
Replacement Avg — Trimmed mean of the middle 40% of active BrickLink stock listings (outlier prices removed). Requires ≥ 10 active lots.
BrickCheck FMV outperforms BrickLink's raw average by blending completed transactions with current market depth, removing both stale low offers and price-gouging high asks.
Every Active 300 constituent must pass all 5 gates simultaneously. Gate evaluation runs after every monthly scrape. Failure on any single gate triggers removal review.
| Gate | Rule |
|---|---|
| G1 | Data quality = Excellent (both markets active, sufficient transaction history) |
| G2 | Total historical sales ≥ 200 (combined new + used) |
| G3 | Both new-condition and used-condition markets active (avg > $0) |
| G4 | Historical used average price > $0 |
| G5 | Historical used transaction volume > 0 |
Total universe: 18,740 minifigures tracked across the BrickLink catalog.
Active constituents: 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 25th 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.
The exact formula, component weights, and normalization methodology are proprietary and are not disclosed publicly. Full score component breakdowns are available to BrickCheck subscribers.
Tier 1 — Immediate (mid-period)
Market collapse: both new + used avg = $0 for 2 consecutive scrapes.
Data quality drop: quality = Bad for 2 consecutive scrapes.
Price spike anomaly: >200% single-period move with <5 transactions — suspended 30 days.
Tier 2 — Annual rebase review
Sales floor breach: total historical sales <150 at review.
Quality degradation: Good quality for ≥2 of last 4 scrapes.
One-sided market: one side = $0 for ≥3 consecutive scrapes.
Rank displacement: liquidity rank <450 at review.
Base period: March 25, 2026 · Index = 100
First headline reading: March 2026 · 164.37 (as of May 29, 2026)
Monthly scrape: 25th 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