Betting Market Glossary

Reading a drop

Drop

A sustained decrease in a price (shortening of odds) over a defined time window, measured from the opening price. A drop signals that the market is revising its probability estimate upward. See The Drop Model.

Opening price

The first widely available number a market trades at before meaningful movement begins. It gives you the baseline from which a drop is measured. Without the opening price, you know the move but not the context.

Curve

The set of prices for the same outcome across different bookmakers at the same moment. A coherent curve — where most books are at or near the same price — suggests a genuine market signal. A scattered curve suggests noise or local adjustments.

Curve coherence

The degree to which the curve moves together. High coherence means multiple relevant books agree with the move. Low coherence means one book may be acting alone.

Limit

The maximum stake a bookmaker will accept on a given market. A rising limit at the reference book alongside a drop qualifies the signal. See Limits, Liquidity, and Signal Quality.

Liquidity

The amount of real money a market can absorb without price distortion. Higher liquidity makes a move more meaningful because it is harder for one bettor to shove the number around.

Timing window

The period over which the drop happened. Fast windows often reflect sharp information or concentrated action. Slow windows often reflect general market drift.

Available price

The best number you can still bet after the market has moved. A signal can be valid even when the available price is no longer attractive.

Book roles

Reference bookmaker

The single book whose price movement drives the read. Pinnacle serves as PhotonOdds' reference bookmaker because it consistently offers the sharpest lines and moves first when sharp money arrives. See Why Pinnacle Is the Reference Bookmaker.

Comparison book

A sharp book whose movement should confirm or diverge from the reference book. Betfair Exchange is a common comparison book. Confirmation strengthens the signal; divergence demands caution.

Alternative book

A soft book where the bettor can actually place the bet. Alternative books are read relative to the reference: the gap between the reference price and the alternative price is the potential window of opportunity.

Sharp book

A bookmaker or exchange whose prices are trusted to reflect informed action quickly. Sharp books usually move earlier, take larger bets, and hold more informational weight than recreational books.

Soft book

A bookmaker that is more consumer-facing, slower to move, or more vulnerable to being picked off on stale prices. Soft books matter because they can lag the sharp market and still offer tradable numbers.

Confirmation

When the reference book and one or more comparison books move in the same direction for the same outcome. Confirmation strengthens the signal.

Divergence

When the reference book moves but comparison books do not, or move in the opposite direction. Divergence does not automatically invalidate the signal but requires explanation.

Stale price

A number that has not yet updated after the rest of the market moved. A stale price can create opportunity, but it can also disappear quickly.

Pricing and process metrics

Implied probability

The probability suggested by a bookmaker's odds. Decimal odds of 2.00 imply a 50% chance before adjusting for margin.

Vig / juice / hold

The bookmaker's built-in margin. This is the gap between fair probability and the priced probability that gives the bookmaker theoretical edge.

No-vig / true odds

A price with the bookmaker's margin removed. No-vig odds represent the market's true probability estimate for each outcome. PhotonOdds derives no-vig prices from the sharp consensus and uses them as the baseline for EV calculations.

Fair price

The odds you would expect if no margin were added. Fair price is the neutral comparison point for evaluating value.

Expected value (EV)

The gap between what a price implies and what you believe the true probability is. Positive EV means the price offers value relative to your estimate. EV is a long-run expectation, not a per-bet guarantee. See EV and CLV: Measuring Process, Not Luck.

Edge

The amount by which a price beats your fair estimate or the market's no-vig price. Edge is often expressed as a percentage.

Closing line

The final widely available sharp-market price before the event starts. It is commonly used as the benchmark for evaluating whether your entry price was strong.

Closing-line value (CLV)

The difference between the price you took and the price at which the market closed. Positive CLV means you beat the final sharp consensus. CLV converges faster than P&L and is a better measure of decision quality over small samples.

ROI

Return on investment. In betting, this usually means profit divided by total stake. It is useful over large samples and noisy over small ones.

Hit rate

The percentage of bets that win. Hit rate alone says little about quality because it ignores price and payout.

Market behaviour and execution

Steam

A rapid, widespread drop in a price driven by concentrated betting volume, typically from sharp accounts. Steam moves faster than normal market adjustment and often triggers alerts in the 5%+ drop range.

Drift

A slower price movement that unfolds over longer periods, often without the sharp structure of classic steam. Drift can still matter, but it is usually less urgent and less tradable.

Steam chase

Betting after the market has already fully corrected simply because the move looked important. Steam chasing is one of the fastest ways to turn a real signal into a bad entry price.

Middle

A situation where two different numbers allow positions on both sides with overlapping win conditions. Middles are related to price dislocation rather than pure arbitrage.

Arbitrage

A situation where two bookmakers price the same event far enough apart that backing every outcome across books locks in a return regardless of the result. Arbs are short-lived and limited by stake availability.

Market correction

The process by which prices move from an inaccurate open toward a better estimate. Not every correction is tradable by the time you see it.

Qualified signal

A move that passes the core reading tests: meaningful change from the open, coherent curve, supportive limit context, sensible timing, and a still-usable available price.

Pass

A deliberate decision not to act on a signal because the context, price, or liquidity is not good enough. Passing is a valid outcome of a strong process.

Common market types

Moneyline

A market where you pick the winner of an event. No handicap, no spread — just which side wins. Also called "1X2" in football when the draw is included.

Draw no bet (DNB)

A market where your stake is returned if the event ends in a draw. Effectively removes the draw from a three-outcome market.

Handicap (Asian handicap)

A market where one side starts with a virtual goal advantage (e.g. −0.5, +1.0). The handicap is applied to the final score to determine the winner. Asian handicap eliminates the draw by using quarter and half-goal lines.

Totals (over/under)

A market on the total number of goals, points, games, or rounds in an event, where you bet over or under a specified line.

Main line

The most liquid, most heavily traded version of a market. Main lines usually deserve more attention than fringe derivatives because the information quality is better.

Derivative market

A secondary market such as correct score, player props, or niche alternatives. Derivative markets can produce real opportunities, but they are more vulnerable to noise and small-limit distortions.

Prop market

A market based on a player or team statistic rather than the core match outcome. Props often require stricter filtering when reading movement because liquidity can vary widely.

Every term on this page shows up on the PhotonOdds Dropping Odds board, where curve, limit movement, and reference-book context are all visible in one place.