Collectors repeat a seasonal catechism: prices dip in January when card money becomes rent money, sag through summer, and rip upward for the holidays. Our index can finally test it, and the test comes back mostly negative, for a humbling reason. In nineteen months of moonstone Pokémon Index history, February 2025 through August 2026, there is not one negative month. The market went up in the alleged January trough, up in the alleged summer doldrums, up in every month we have measured.
moonstone Pokémon Index, monthly average
The seasons show up anyway, as fast and slow
A market that never falls can still have rhythm, and this one does. The two slowest months on the tape are exactly where folklore predicts weakness: January 2026 at +1.8% and November 2025 at +2.2%. The hottest stretch is spring into early summer 2026, three straight months between +8.5% and +8.9%, with August 2025 (+7.7%) the prior peak. So the seasonal story survives in miniature: the January effect is real, it just meant decelerating instead of declining, because an overwhelming bull trend swamped it.
That is also the honest limitation of this study. Nineteen months is one market regime, and it happened to be a historic one. We cannot tell you what Pokémon seasonality looks like in a flat market, because our index has never seen a flat market. What we can tell you is that anyone who waited for the traditional January dip to buy in 2026 paid 1.8% more instead, and anyone waiting for a summer lull watched the fastest quarter on record.
moonstone Pokémon Index, weekly points read on August 26, 2026, covering February 24, 2025 through August 26, 2026 (231.4), averaged by calendar month; month-over-month changes computed on those averages. Two corrections to how this was first described, made 2026-09-22 after reading the index code rather than recalling it. The index carries no fixed base date: it is recomputed each run over a rolling 550-day window, so February 24, 2025 is simply 550 days before the read above and has since rolled forward, and earlier levels are rewritten on each run. And its constituent set is fixed only as a stored basket, which the builder re-derives if that stored row is ever lost. The index is genuinely equal-weight, dividing each constituent by its own base before averaging, which is the part that was right. Nineteen months covers a single sustained bull regime; no claim here extends to other regimes. Re-verified 2026-09-22 by an independent recomputation against the stored index, and the finding holds on a window that has since rolled to March 24, 2025 through September 22, 2026: every calendar month is still positive, January is still the slowest at +2.06% and November second at +2.13%, and the level now reads 236.87 on a base that is no longer February 2025. Because the window rolls, the levels charted above belong to the August 26, 2026 read and cannot be reproduced from today's series. Not financial advice.