Loss aversion explains why realizing red stings. 13.6 adds the ownership twist: once a contract is yours, you mentally inflate its value. The endowment effect is why you refuse to sell a fading YES at fair mark, why entry price feels sacred, and why play-money positions feel too good to close before you move real USD on a regulated venue.
This is not loyalty to a thesis—it is status quo bias wearing a portfolio jersey. The module now connects feeling, selective evidence, sticky numbers, inflated skill, and loss pain to hold decisions that violate expected value.
What endowment is (and is not)
Endowment effect: owning an object raises willingness-to-accept versus willingness-to-pay. Symptom: “I need 72¢ to sell” when you would only buy at 58¢.
Disposition effect sells winners early and keeps losers—often co-occurring. Sunk cost cites past effort as reason to continue. Anchoring makes entry cost feel “fair.” Identity treats candidate YES as self—not a bond.
Closing because resolution criteria changed or a thesis stop fired is discipline, not endowment. If you would not buy a stranger’s position at today’s price, you should not keep yours merely because it already sits in the wallet.
Why binary contracts amplify ownership
Named outcomes feel like support, not a position. Visible P&L ties ego to mark. Illiquid exit breeds “trapped” magical thinking. Long duration builds relationship with a contract. Social screenshots raise reputation cost of selling.
Price approximates probability in theory; endowment makes your lot feel like the true probability. That is why two traders can watch the same mid and disagree only because one is flat and one is long—same information, different ownership psychology.
Identity markets
Politics, culture, and fandom markets are identity-heavy. If taking the other side feels like betrayal, reduce size or shadow-trade until you can write the NO case without contempt. Endowment plus identity is the hardest hold to exit; systems matter more, not less.
WTA versus WTP on the trading floor
Classic mug experiments: owners demand about twice what buyers pay. In markets ask: would you buy this at today’s price? If no, you are likely overholding. Would you sell at today’s price? If yes at fair mark, belief should match.
Every hold review starts with blind re-buy: if flat, would you open this size at this price? No means exit or resize.
Marquee hold (worked example)
You bought YES on “Fed cuts in March” at 48¢; CPI runs hot; price 41¢; journal still says 52% without new evidence.
Endowment says locking loss is unbearable and you would never buy more at 41¢. Clean process refreshes probability toward high forties against low forties market—trim or exit; ban “wait for 48¢” as anchor, not thesis. Markets do not owe you your entry.
Play money infecting real money (worked example)
Manifold YES at 70% feels like a trophy; Kalshi equivalent near 63¢ after fees. You never sell Manifold because it is your profile.
Sunday mark-to-market on shadow books. Re-buy test: would you add at 70%? If no, close. No USD size-up until shadow exit is logged. Play-money endowment trains attachment without pain—dangerous before real bankroll caps.
Pairings with other biases
Overconfidence says “they’re wrong at 41¢.” Loss aversion doubles hold on losers. Confirmation feeds only dovish takes. Affect makes selling feel like betrayal—write probability before social media.
Hedging is risk reduction, not clinging to every leg in a correlated tree. Sell winners when probability falls below price; cut losers when thesis dies.
Liquidity and the “can’t sell” story
Wide spread is not permission to hold a dead thesis—pay slippage in expected value. Automated market maker prices reflect flow, not mean reversion to your entry. Pre-halt rules mean reduce size before you are stuck, not after.
If exit costs three cents and thesis is dead, pay three cents—cheaper than weeks of bias tax.
Ownership detox (fifteen minutes per position)
Hide entry in the journal; write current price and probability only. Answer blind re-buy yes, no, or smaller. Compare belief to consensus price and cross-venue dispersion. If NO case stronger than at entry, exit regardless of P&L color. Set thesis stop text independent of cents lost. High emotion plus re-buy no means no market orders.
Weekly target: zero open positions where re-buy is no.
Entry friction prevents future endowment
Before new risk: explain resolution in one sentence; verify edge after fees; half-Kelly if first trade in the event; sketch exit evidence not exit price; thirty-minute cooldown after headlines.
Buying with an exit sketch lowers endowment—you purchased a process, not a trophy. The sketch should name evidence, not “sell at seventy cents.” Evidence-based exits age better when resolution surprises you.
Correlated trees and “my leg”
Multi-outcome trees tempt you to love one leg because you researched it deepest. Joint expected value across legs is the portfolio object; hugging one child contract because it is yours is endowment at tree scale. Review the whole tree on Sunday, not each leg only when green.
Red flags
Waiting to break even is anchoring plus loss aversion. “My market” loyalty is venue endowment. Illiquid so I hold is narrative, not math.
Gifting and transfers
Receiving a position as a gift or transfer triggers endowment instantly—you did not even pay the anchor price yet still overvalue. Re-run blind re-buy the day any wallet changes hands.
Size drift
Endowment also pushes size up on positions you already hold—“I know this one” becomes extra shares without a fresh gate. Treat adds like new entries: full pre-trade gate, not a tap because the lot is already green.
Watchlists versus positions
Watchlist names feel neutral; owned names feel urgent. Review watchlist probabilities weekly without ownership; compare to held names the same day. Divergence often reveals endowment, not new information. If held names always look more bullish than watchlist names, ownership is pricing your beliefs.
What comes next
Ownership distorts exits; recency distorts timing of belief—overweighting the last poll, print, tweet, or tick. The next chapter covers scheduled updating versus feed refresh.
Next: Recency Bias: Overweighting the Last Thing You Heard