Sum-to-one and ladder arbitrage across whole events
Multi-outcome events must sum to $1; probability ladders must be monotonic. Scanners find "violations" all day long. Then you check the live book, and nearly every one is a mirage.
The hypothesisA multi-outcome event whose YES prices sum away from $1.00, a binary whose YES+NO ≠ $1, or a ladder where P(X > high) exceeds P(X > low) is a structural mispricing — scan every event continuously and harvest the violations.
The test
Three scanners ran continuously across the full active universe, flagging violations from indexed price data — then, following the "detect wide, act narrow" discipline, every flag was re-priced at the live executable order books (the actual asks a basket buyer pays, the actual bids a ladder seller receives) and cross-checked against recent traded volume, because a resting quote on a token nobody trades is not evidence of a fillable gap.
The result
The overwhelming majority of flagged violations were mirages — artifacts of cached or indicative prices that vanished at the live book. Most of the remainder failed the staleness check: quotes on untraded outcomes that would move the moment anyone approached them. The genuinely executable residue was rare, small, and concentrated below the threshold where fees plus multi-leg fill risk consume the gap — a finding consistent with published academic measurement of these markets, which is why a hard minimum-gap floor now guards the executor and it essentially never fires. Near-settled events produced the most seductive false positives: a basket summing to $1.04 because one leg is resolving is settlement mechanics, not arbitrage.
Conclusion
Structural consistency is enforced by professional flow faster and tighter than an external scanner can exploit. The scanners stay on as instrumentation — the mirage rate itself is useful telemetry about data staleness — but as a profit strategy, whole-event arbitrage on these markets joins the same graveyard as the candle version: real in screenshots, absent at the book. If your arbitrage dashboard shows opportunities all day, your dashboard is what's mispriced.