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Glossary

43 terms you need to trade prediction markets seriously. Definitions are grounded in how World actually works on Solana, and examples use numbers we measured on our own index.

01

The basics

8 TERMS
Prediction market

A market where shares pay $1 if an outcome happens and $0 if it does not. The price of a share is the market's probability estimate.

WHY THIS MATTERS

YES at 62c means the market thinks the event is 62% likely.

YES / NO shares

The two sides of a binary market. One YES plus one NO always redeems for exactly $1, so their prices always sum to $1.

Settlement

The moment a market's outcome becomes final and winning shares pay out $1 each. On World this happens on-chain, typically within a minute of resolution.

Resolution

The determination of which side won. Crypto rounds resolve from price feeds; sports resolve from results.

CASH

The Token-2022 stablecoin World markets settle in. All dollar figures on Foreteller are real CASH amounts.

Round

A short repeating market, like BTC Up, that asks whether a price will be higher at the end of a few minutes. New rounds open continuously.

Escrow / mint

Depositing $1 of collateral mints one YES and one NO share. Burning a matched pair redeems the $1. This is what makes prices probabilities.

Redemption

Exchanging winning shares for CASH after settlement. Losing shares burn worthless. On World, redemptions are keeper-executed, so winners do not sign their own payout.

02

Prices and probability

8 TERMS
Implied probability

The price read as a percentage. A 30c share implies 30%. If your own estimate is higher, the share is value; if lower, it is overpriced.

Calibration

Whether prices match reality over many markets. Perfectly calibrated 70c contracts win exactly 70% of the time.

WHY THIS MATTERS

On World, closing prices are nearly perfectly calibrated: 97c closes win about 95% of the time. Mid-life prices are not.

Expected value (EV)

What a bet is worth on average: probability x payout minus cost. Positive EV is the only reason to enter a trade.

WHY THIS MATTERS

Buying at 25c an outcome you correctly believe is 35% likely earns 10c per share on average.

Edge

Realized outcome minus entry price, per share. The core skill measure: buy at 40c, outcome wins, edge is +60c; it loses, edge is -40c. Averaged over many calls, edge separates skill from luck.

Closing line value (CLV)

The market's final price minus your entry price. Beating the close consistently means you saw fair value before the market did, the gold-standard skill signal from sports betting.

Vig / vigorish

The margin a venue builds into prices. When YES plus NO cost more than $1, the difference is vig.

WHY THIS MATTERS

World runs zero vig: YES plus NO sum to exactly $1. The cost of trading lives in the spread instead.

Longshot bias

The tendency for low-probability outcomes to be over- or under-priced. On World we measured the opposite of the classic bias: 3-8c tails have historically won 2-3x their implied rate.

Favorite

The side priced above 50c. Our data shows World favorites in the 60-72c band have won only about 48% of the time, far below what their price implies.

03

Market structure

8 TERMS
AMM (automated market maker)

A program that quotes prices and takes the other side of every trade. On World, the Janus AMM is the sole counterparty; there is no order book.

Keeper

The bot that updates the AMM's quotes. It reprices on new information in discrete steps, not continuously, which is why quotes can briefly go stale.

Spread

The gap between what you pay buying and receive selling. World has no explicit spread, but quote stickiness creates an effective spread we measured at roughly 5c round trip on mid-priced contracts.

Slippage

Price movement caused by your own order size. Thin markets move more; our paper trading simulates this honestly because real fills would too.

Depth / liquidity

How much size a market can absorb without moving. On World, depth is one balance sheet (the AMM pool), and edge has historically degraded above roughly $5k positions.

Mid-life price

The price during a market's life, before it converges to the truth near close. This is where World prices are least reliable, and where the edge lives.

In-play

Trading while the underlying event is happening, like a match or an open crypto round. Prices move fast and stale quotes appear.

Oracle

The source of truth a market resolves against, like a price feed for crypto rounds.

04

Risk and bankroll

7 TERMS
Bankroll

The capital you can afford to lose entirely, managed as a unit. Every sizing rule is expressed as a fraction of it.

Kelly criterion

The formula for optimal bet sizing given your edge: bet a fraction of bankroll proportional to your advantage. Most professionals bet a half or quarter Kelly because overestimating edge is easy.

Variance

The randomness in outcomes even when your decisions are right. Binary markets are high variance; a real 60% edge still loses 4 times in 10.

Drawdown

The distance from your bankroll's peak to its lowest point after. Survivable drawdown is the design constraint for sizing.

Ruin

Losing the bankroll before your edge can express itself. Betting too large converts a winning strategy into a losing one.

Tilt

Making bigger, worse bets after losing. Detectable in the data as sizing up after drawdowns; the discipline metric on Foreteller profiles measures the opposite.

Hedging

Holding both sides of a market to reduce risk. Legitimate for locking profit; our skill scoring nets hedged pairs out so they cannot inflate confidence.

05

Skill measurement (the Foreteller layer)

12 TERMS
fscore

Foreteller's 0-100 forecasting skill score: the lower confidence bound of your average edge per call, mapped through a logistic. It answers 'how sure are we this is skill, not luck'. One lucky hit cannot fake it; many small good calls cannot hide.

Scored call

One (market, side) position held to resolution, with entry price, size, and outcome recorded permanently. The unit of the skill dataset.

Worst-case edge

The lower 90% confidence bound on your mean edge. Positive worst-case edge over many calls is the strongest evidence of real skill.

Capacity

How much size a trader's edge survives. Measured as size-weighted edge versus average edge: if your bigger bets do worse, your capacity is small, and funding decisions respect that.

Consistency

The share of your active trading days with positive average edge. Skill shows up repeatedly; luck clusters.

Sizing discipline

The correlation between your stake and your realized edge. Positive means you bet bigger when you are right more, the Kelly instinct.

Sample size

The number of scored calls behind a statistic. Small samples mean nothing: 10 wins proves less than 60% over 200 calls. All Foreteller scores shrink toward neutral on small samples.

Paper trading

Trading virtual capital at real market prices, settled by real outcomes. On Foreteller it is the evaluation layer: prove skill on paper, graduate to funded capital.

Funded account / vault

Capital allocated to a proven trader, sized by their scores, with profits split. The graduation prize of the whole ecosystem.

First-loss stake

A refundable deposit a funded trader posts that absorbs initial losses, aligning incentives between trader and capital.

Wash trading

Trading with yourself or in circles to fake volume or records. The skill engine filters it: hedged pairs are netted, dust is floored, and confidence bounds punish thin samples.

Sybil

Splitting activity across many wallets to farm rewards or reroll luck. Confidence-bound scoring makes this self-defeating: each wallet has fewer calls, so each scores lower.

Next step

Terms make sense with skin in the game. Learn them in order in the Academy, then try them with $10,000 of practice capital in the Playground.