Reversal Index

When large wallets pile into one side of a Polymarket contract, does the market move their way? This page records those positions before the outcome is known, and scores them against the probability the market itself was quoting at the moment the money went in.

That last part is the whole point. A hit rate on its own says nothing: if whales bought at 60¢, the market was already calling it a 60% shot, and being right 60% of the time is not insight — it is the price. The only number worth reporting is the margin over the market, with the error bars attached.

Live ledger — positions recorded in advance

Positions
6
6 open
Market implied
at entry
Actually landed
0 graded

Too few graded positions to mean anything yet. This section will not be presented as a finding until at least 30 have resolved and the result survives a significance test.

MarketWhales backedMarket saidOutcome
Will there be no change in Fed interest rates after the July 2026 meeting?
recorded 2026-07-27 · 25 wallets · $1.3M
Yes83¢open
San Diego Padres vs. Atlanta Braves
recorded 2026-07-27 · 5 wallets · $136k
Atlanta Braves70¢open
UFC Freedom 250: Ciryl Gane vs. Alex Pereira (Heavyweight, Main Card)
recorded 2026-07-27 · 3 wallets · $130k
Alex Pereira52¢open
Houston Astros vs. Chicago White Sox
recorded 2026-07-27 · 3 wallets · $130k
Chicago White Sox51¢open
LoL: Top Esports vs ThunderTalk Gaming (BO3) - LPL Group Ascend
recorded 2026-07-27 · 6 wallets · $127k
Top Esports71¢open
LoL: ThunderTalk Gaming vs EDward Gaming - Game 2 Winner
recorded 2026-07-27 · 3 wallets · $116k
ThunderTalk Gaming55¢open

The baseline, and why it proves nothing

Before committing to anything forward-looking we scored 83 positions that had already resolved. Whale-backed outcomes landed 66% of the time. The market was quoting 59% when they bought. That is an edge of 7.1 points — about 6 extra wins over 83 bets.

Graded
83
positions
Market implied
59%
at entry
Landed
66%
observed
p-value
0.16
not significant

A 66% hit rate reads well, and it would be easy to put it on a chart and stop there. It does not hold up. The 95% confidence interval runs from 56% to 76%, and the market's own 59% sits inside it. At p = 0.16, chance explains the gap comfortably.

This is the question our first backtest could not answer: back then only three markets were both genuinely contested and heavily whale-funded, which is no sample at all. It is 83 now, and the answer is still the same one.

There is a second, worse problem. We chose the selection bars after looking at this data. Criteria fitted to a sample will always flatter it, so no backtest run this way can settle the question, however large it gets. That is the reason the live ledger exists at all — it is the same measurement with the fitting removed.

All 85 baseline positions
MarketWhales backedMarket saidOutcome
Will Spain win the 2026 FIFA World Cup?
recorded 2026-07-21 · 48 wallets · $2.9M
Yes59¢right
Will Argentina win the 2026 FIFA World Cup?
recorded 2026-07-21 · 24 wallets · $1.5M
Yes32¢wrong
Will France win on 2026-07-18?
recorded 2026-07-21 · 20 wallets · $1.3M
Yes53¢wrong
Will United States win on 2026-07-06?
recorded 2026-07-21 · 5 wallets · $1.1M
No64¢right
Spurs vs. Knicks
recorded 2026-07-21 · 3 wallets · $936k
Spurs47¢right
Will Morocco win on 2026-06-24?
recorded 2026-07-21 · 6 wallets · $910k
Yes65¢right
Spread: France (-2.5)
recorded 2026-07-21 · 3 wallets · $809k
Iraq43¢wrong
Will Japan win on 2026-06-25?
recorded 2026-07-21 · 7 wallets · $777k
No59¢right
Will France win on 2026-07-14?
recorded 2026-07-21 · 6 wallets · $774k
No63¢right
Will Spain win on 2026-07-19?
recorded 2026-07-21 · 9 wallets · $719k
No58¢right
Will France win on 2026-07-09?
recorded 2026-07-21 · 13 wallets · $638k
Yes69¢right
Will Argentina win on 2026-06-22?
recorded 2026-07-21 · 7 wallets · $613k
Yes71¢right
France vs. England: Team to Win
recorded 2026-07-21 · 19 wallets · $557k
France64¢wrong
Will Spain vs. Argentina end in a draw?
recorded 2026-07-21 · 8 wallets · $535k
Yes36¢right
France vs. Spain: Team to Advance
recorded 2026-07-21 · 7 wallets · $522k
Spain43¢right
Will Argentina win on 2026-07-19?
recorded 2026-07-21 · 12 wallets · $522k
No74¢right
Will Argentina win on 2026-07-03?
recorded 2026-07-21 · 9 wallets · $521k
No73¢right
England vs. Argentina: Team to Advance
recorded 2026-07-21 · 9 wallets · $518k
Argentina49¢right
Mexico vs. Ecuador: Team to Advance
recorded 2026-07-21 · 4 wallets · $509k
Mexico63¢right
Will Japan win on 2026-06-21?
recorded 2026-07-21 · 3 wallets · $505k
Yes70¢right
Will Morocco win on 2026-06-19?
recorded 2026-07-21 · 6 wallets · $484k
No41¢wrong
Will United States win on 2026-06-12?
recorded 2026-07-21 · 9 wallets · $483k
Yes63¢right
Will Belgium win on 2026-06-21?
recorded 2026-07-21 · 6 wallets · $451k
Yes64¢open
UFC Fight Night: Kamaru Usman vs. Dricus Du Plessis (Middleweight, Main Card)
recorded 2026-07-21 · 9 wallets · $445k
Dricus Du Plessis67¢right
Will France win the 2026 FIFA World Cup?
recorded 2026-07-21 · 15 wallets · $442k
Yes27¢wrong
Will Germany win on 2026-06-20?
recorded 2026-07-21 · 13 wallets · $441k
Yes71¢right
Will Netherlands win on 2026-06-20?
recorded 2026-07-21 · 5 wallets · $410k
Yes63¢right
Will Croatia win on 2026-06-23?
recorded 2026-07-21 · 3 wallets · $403k
Yes84¢right
Will England win on 2026-07-18?
recorded 2026-07-21 · 13 wallets · $371k
Yes60¢right
Will Scotland win on 2026-06-13?
recorded 2026-07-21 · 9 wallets · $366k
No37¢wrong
Will Belgium win on 2026-06-15?
recorded 2026-07-21 · 3 wallets · $352k
Yes66¢wrong
Will the New York Knicks win the 2026 NBA Finals?
recorded 2026-07-21 · 4 wallets · $348k
Yes80¢right
Will Croatia win on 2026-06-27?
recorded 2026-07-21 · 5 wallets · $328k
Yes57¢right
Mexico vs. England: Team to Advance
recorded 2026-07-21 · 11 wallets · $315k
England56¢right
Portugal vs. Spain: O/U 2.5
recorded 2026-07-21 · 3 wallets · $311k
Over55¢wrong
Spread: Spain (-1.5)
recorded 2026-07-21 · 6 wallets · $306k
Argentina80¢right
Australia vs. Egypt: Team to Advance
recorded 2026-07-21 · 4 wallets · $306k
Australia44¢wrong
Will France win on 2026-07-04?
recorded 2026-07-21 · 10 wallets · $302k
Yes83¢right
Spread: England (-2.5)
recorded 2026-07-21 · 5 wallets · $298k
Panama55¢right
Will Egypt win on 2026-06-21?
recorded 2026-07-21 · 5 wallets · $282k
No45¢wrong
Will IR Iran win on 2026-06-15?
recorded 2026-07-21 · 5 wallets · $281k
Yes54¢wrong
Will England win on 2026-07-15?
recorded 2026-07-21 · 4 wallets · $280k
Yes40¢wrong
France vs. Morocco: Team to Advance
recorded 2026-07-21 · 5 wallets · $241k
France78¢right
France vs. England: O/U 3.5
recorded 2026-07-21 · 5 wallets · $217k
Over45¢right
Spain vs. Cabo Verde: O/U 3.5
recorded 2026-07-21 · 3 wallets · $210k
Under47¢right
Will France win on 2026-06-30?
recorded 2026-07-21 · 5 wallets · $206k
No23¢wrong
Will Norway win on 2026-06-22?
recorded 2026-07-21 · 6 wallets · $206k
Yes82¢right
Will Colombia win on 2026-07-07?
recorded 2026-07-21 · 5 wallets · $203k
No59¢right
Spain vs. Argentina: O/U 1.5
recorded 2026-07-21 · 7 wallets · $198k
Over65¢wrong
France vs. England: Both Teams to Score
recorded 2026-07-21 · 8 wallets · $197k
No32¢wrong
Will Brazil win on 2026-07-05?
recorded 2026-07-21 · 5 wallets · $197k
Yes54¢wrong
Portugal vs. Spain: Team to Advance
recorded 2026-07-21 · 4 wallets · $179k
Spain67¢right
Spurs vs. Knicks
recorded 2026-07-21 · 5 wallets · $171k
Spurs77¢wrong
Argentina vs. Egypt: Team to Advance
recorded 2026-07-21 · 5 wallets · $171k
Argentina83¢right
LoL: T1 vs Gen.G (BO3) - Esports World Cup Playoffs
recorded 2026-07-21 · 8 wallets · $169k
Gen.G67¢right
LoL: T1 vs Karmine Corp - Game 1 Winner
recorded 2026-07-21 · 3 wallets · $163k
T174¢right
LoL: T1 vs Gen.G - Game 1 Winner
recorded 2026-07-21 · 7 wallets · $160k
Gen.G84¢right
United States vs. Belgium: Team to Advance
recorded 2026-07-21 · 4 wallets · $159k
United States54¢wrong
Will Mexico win on 2026-06-18?
recorded 2026-07-21 · 7 wallets · $154k
Yes55¢right
Knicks vs. Spurs
recorded 2026-07-21 · 4 wallets · $153k
Knicks33¢right
Will Germany win on 2026-06-29?
recorded 2026-07-21 · 3 wallets · $145k
Yes74¢wrong
Mexico vs. Korea Republic: O/U 2.5
recorded 2026-07-21 · 4 wallets · $139k
Under57¢right
Will Senegal win on 2026-06-22?
recorded 2026-07-21 · 4 wallets · $136k
No82¢right
Will England win on 2026-06-23?
recorded 2026-07-21 · 4 wallets · $135k
Yes81¢wrong
Will Mexico win on 2026-07-05?
recorded 2026-07-21 · 4 wallets · $129k
No85¢right
UFC Fight Night: Chase Hooper vs. Mitch Ramirez (Lightweight, Main Card)
recorded 2026-07-21 · 3 wallets · $126k
Mitch Ramirez24¢wrong
Will Portugal win on 2026-07-02?
recorded 2026-07-21 · 5 wallets · $125k
Yes57¢right
Will Spain win on 2026-07-14?
recorded 2026-07-21 · 5 wallets · $125k
Yes53¢right
Exact Score: Spain 0 - 0 Argentina?
recorded 2026-07-21 · 3 wallets · $125k
Yes20¢right
Will United States win on 2026-07-01?
recorded 2026-07-21 · 3 wallets · $123k
Yes74¢right
Spread: Germany (-1.5)
recorded 2026-07-21 · 3 wallets · $120k
Germany48¢wrong
Spread: England (-1.5)
recorded 2026-07-21 · 3 wallets · $120k
England59¢wrong
Will Türkiye win on 2026-06-25?
recorded 2026-07-21 · 3 wallets · $118k
Yes28¢right
UFC Freedom 250: Justin Gaethje vs. Ilia Topuria (Lightweight, Main Card)
recorded 2026-07-21 · 4 wallets · $118k
Ilia Topuria79¢wrong
Will Brazil win on 2026-06-13?
recorded 2026-07-21 · 5 wallets · $117k
No66¢right
Los Angeles Dodgers vs. New York Yankees
recorded 2026-07-21 · 5 wallets · $116k
Los Angeles Dodgers63¢right
Iran agrees to end enrichment of uranium by June 30?
recorded 2026-07-21 · 3 wallets · $113k
No72¢right
Will Switzerland win on 2026-07-02?
recorded 2026-07-21 · 5 wallets · $112k
Yes72¢right
Will Croatia win on 2026-06-17?
recorded 2026-07-21 · 4 wallets · $111k
No84¢right
Will Uruguay win on 2026-06-21?
recorded 2026-07-21 · 4 wallets · $110k
Yes67¢wrong
Athens Open: Tereza Valentova vs Alina Korneeva
recorded 2026-07-21 · 3 wallets · $108k
Tereza Valentova64¢wrong
Will Switzerland vs. Colombia end in a draw?
recorded 2026-07-21 · 3 wallets · $108k
Yes34¢right
France vs. Iraq: 1st Half O/U 1.5
recorded 2026-07-21 · 3 wallets · $107k
Over55¢wrong
Will DR Congo win on 2026-06-27?
recorded 2026-07-21 · 4 wallets · $102k
Yes58¢right
Will United States win on 2026-06-25?
recorded 2026-07-21 · 5 wallets · $101k
No56¢open

Method

  • What counts as whale flow. Individual fills of $10k or more, from the on-chain trade tape.
  • What makes a position. A market needs at least $100k of such fills across 3 or more wallets, with at least 65% of bought notional on one side.
  • It has to be a real call. The notional-weighted entry price must sit between 15¢ and 85¢. Buying at 97¢ is not a prediction, and including it would inflate the hit rate without adding information.
  • Grading. We have no official resolution feed, so a position is scored when one outcome's last print reaches 97¢. Markets that go quiet below that stay open instead of being scored against whichever side happened to be ahead. This is a proxy for resolution, not an oracle.
  • Nothing is revised. Once recorded, a position's market, side, entry price and date are frozen; the only fields that can ever change are the outcome and the date it landed.
  • What this is not. Not profit and loss — it ignores position sizing, fees and exits. Not advice. Wallets are identified by address only; no attempt is made to say who is behind one.

Data as of 2026-07-27. Related: whale activity by market · whale index