The GPK25 Index
The market barometer for Garbage Pail Kids: an equal-weighted index of 25 benchmark cards — one exact card at one exact grade — chain-linked monthly from real recorded sales. Base 1000.
Index history — 2025-03 to 2026-06
The 25 constituents
Fixed for the year (reconstituted every Jan 1). ANCHOR cards are permanent. STALE = fewer than 3 sales in the current 90-day window, so the last median is carried.
| Card | Series | Grade | Segment | 90d median | Sales | 1M% | 12M% | |
|---|---|---|---|---|---|---|---|---|
| #1A Nasty Nick | OS1 | PSA 8 | os1_key | $1,095.00 | 3 | -8.7% | +28.8% | ANCHOR |
| #8A Adam Bomb | OS1 | PSA 8 | os1_key | $550.00 | 32 | +0.0% | +37.5% | ANCHOR |
| #18A Cranky Frankie | OS1 | PSA 10 | premium | $355.00 | 5 | -0.6% | +98.8% | |
| #1B Evil Eddie | OS1 | PSA 8 | os1_key | $346.46 | 5 | +38.6% | +65.0% | ANCHOR |
| #18B Bad Brad | OS1 | PSA 10 | premium | $333.00 | 5 | -4.6% | +26.3% | |
| #4A Fryin' Brian | OS1 | PSA 8 | os1_key | $204.75 | 4 | +2.9% | +66.1% | |
| #53B Live Mike | OS2 | PSA 9 | os2 | $115.00 | 3 | +0.0% | +130.0% | |
| #14A Potty Scotty | OS1 | PSA 8 | os1_field | $83.99 | 3 | +20.0% | +15.8% | |
| #39A Buggy Betty | OS1 | PSA 8 | os1_field | $75.00 | 2 | +0.0% | +87.5% | STALE |
| #2B Ray Decay | OS1 | PSA 8 | os1_key | $74.99 | 3 | +0.0% | — | |
| #40A Unstitched Mitch | OS1 | PSA 8 | os1_field | $71.50 | 4 | -5.9% | +30.0% | |
| #15A Ailin' Al | OS1 | PSA 8 | os1_field | $64.50 | 4 | +9.3% | +30.3% | |
| #23B Leaky Lou | OS1 | PSA 8 | os1_field | $64.00 | 2 | +0.0% | +42.3% | STALE |
| #36B Tommy Tomb | OS1 | PSA 8 | os1_field | $60.50 | 6 | +0.0% | -2.4% | |
| #11A Itchy Richie | OS1 | PSA 8 | os1_field | $59.69 | 7 | +1.2% | +61.3% | |
| #3A Up Chuck | OS1 | PSA 8 | os1_key | $45.00 | 3 | -51.9% | -34.8% | |
| #33A Mad Mike | OS1 | PSA 8 | os1_field | $43.00 | 1 | +0.0% | -25.9% | STALE |
| #37A Guillo Tina | OS1 | PSA 8 | os1_field | $40.42 | 6 | -1.4% | +1.2% | |
| #132A Bony Tony | OS4 | PSA 9 | os4_5 | $36.00 | 7 | +0.0% | +132.3% | |
| #132B Unzipped Zack | OS4 | PSA 9 | os4_5 | $26.99 | 5 | -0.1% | +80.1% | |
| #172A Nat Nerd | OS5 | PSA 9 | os4_5 | $26.99 | 7 | -1.8% | +8.0% | |
| #100A Ali Gator | OS3 | PSA 9 | os3 | $20.00 | 2 | +0.0% | +48.1% | STALE |
| #153B Duncan Pumpkin | OS4 | PSA 9 | os4_5 | $17.30 | 2 | +0.0% | +15.4% | STALE |
| #133B Foxy Francis | OS4 | PSA 9 | os4_5 | $13.50 | 3 | +5.9% | +31.7% | |
| #96A Distorted Dot | OS3 | PSA 9 | os3 | $7.49 | 0 | +0.0% | -46.5% | STALE |
Methodology
Constituents. 25 fixed constituents; each is one exact card at one exact grade from one grader (PSA). Five flagship OS1 cards plus Adam Bomb 8a PSA 9 are permanent anchors; the rest were selected by trailing-12-month dollar volume within segment quotas (eligibility: at least 12 recorded sales at the benchmark grade in the trailing 12 months; quota slots a segment cannot fill shift to the OS1 field pool, then OS2).
Pricing. A constituent's value for month M is the median of its recorded sales in the 90 days ending the last day of M (dates US/Eastern). Fewer than 3 sales: the last median is carried forward and the month is flagged stale. Sales above 5x or below 0.2x the trailing median are excluded as outliers, along with sales our pipeline flags as suspect. Real sales only — never estimates.
Index math. Equal-weighted and chain-linked: each month's return is the simple average of constituent month-over-month changes (carried values count), and the level compounds from 1000 at inception (2025-03, the first month where at least 20 of 25 constituents had fresh medians). Constituent swaps are spliced through the chain — the outgoing card's final month still counts and the incoming card starts the next full month — so list changes never jump the level.
History & maintenance. Months before 2026-07 are backtested (computed with today's constituent list, shown dashed). The current month is recomputed daily as provisional (dotted) and is never chained until it closes. The list is reconstituted every Jan 1 (first: 2027): anchors never leave; a non-anchor is replaced only after logging fewer than 12 sales in both Q3 and Q4, at most 5 swaps per year. Mid-year, the only allowed changes are an automatic swap after 6 consecutive stale months and data corrections. Method v1.