Event Correlation
Definition
Event correlation is the degree to which the outcomes of different event contracts depend on each other. Markets on related events, such as the same election, the same economic release or the same game, tend to resolve together, so holding several of them concentrates rather than spreads risk. Correlation also affects products that combine events, which price the joint probability rather than the separate ones.
Why it matters
Correlation hides concentration. Ten small positions that all depend on one event are one large position, and a combo of correlated legs can be mispriced if a trader assumes independence. Investors should identify shared drivers before sizing, and treat related positions as a single risk.
Common misconceptions
- •Different markets are not independent bets.
- •Multiplying leg prices assumes independence; correlated legs are worth more or less than that product.
- •A hedge in a related market can fail if the correlation is weaker than assumed.
- •The label is only a starting point. Investor outcomes usually depend on the governing documents, cash-flow priority, valuation policy, disclosure quality, and manager discretion surrounding the term, not just the shorthand definition used in marketing materials.
Technical details
Worked example (illustrative): two related legs
Leg A priced 50 cents, leg B priced 50 cents.
If independent, both happen 25% of the time; a combo would be worth about 25 cents.
If B nearly always happens when A does, both happen close to 50% of the time.
A trader who multiplies prices as if independent undervalues the combination; one who assumes they always go together overvalues it when they do not.
How investors apply the term
Investors usually apply this term by tying the definition back to the controlling documents and then asking which cash flows, rights, restrictions, or valuation assumptions it changes. A useful review looks at the term alongside fees, leverage, liquidity, reporting frequency, and manager discretion rather than treating it as a standalone concept.
The practical diligence test is simple: identify who benefits if the assumption is wrong, who has control when conditions change, and what evidence the investor receives after closing. Terms that cannot be reconciled to documents, cash movements, and monitoring data should be treated as marketing shorthand until proven otherwise.
Frequently asked questions
- Why is buying several related markets not necessarily diversification?
- Because one underlying outcome can decide them all. Positions on a candidate winning a state, winning the national vote and a party winning the chamber may all depend on the same turnout and polling error. If that common factor goes against you, they lose together.
- How do combos handle correlated events?
- They price the combination. Kalshi combos 'resolve to the product of the underlying positions' and pay at most $1.00; 'if any position settles at $0, the entire combo pays $0.' Combo prices come from a request-for-quote system in which participants quote the specific combination, so their prices reflect how related the legs are, not just each leg's price.
- How should I think about correlation?
- Map the drivers. List what has to happen for each position to win and look for shared causes: the same data release, the same person, the same game. Positions that share a driver should be counted as one exposure when sizing.