Horse racing flucs, short for fluctuations, are a runner's price history from the moment its market opens to the jump: where it opened, how high and low it went, and where it is now. Racing Victoria's glossary defines a fluctuation as a runner's odds movement as dictated by betting activity. With illustrative prices, a line that opened at $8.00, went out to $9.00, came in to $5.50 and now sits at $6.00 shows a runner the market rates more highly than at the open. The last move, from $5.50 back to $6.00, is a small ease.
Flucs show how money and opinion have moved, not how the race will be run. Read for the size of a move, where it happened and when, they show how the market reached the price you are about to take. Where flucs sit among the other price types and settlement rules is mapped in horse racing betting.
How to read a fluc line: open, high, low and current
The illustrative line from the opening paragraph, point by point, with each price turned into an implied chance (1 / price):
| Point in the market | Price | Implied chance |
|---|---|---|
| Opening price, the afternoon before | $8.00 | 12.5% |
| Race morning (the high) | $9.00 | 11.1% |
| Late morning | $7.50 | 13.3% |
| 30 minutes before the jump | $6.00 | 16.7% |
| 5 minutes before (the low) | $5.50 | 18.2% |
| Current, 1 minute before | $6.00 | 16.7% |
Four numbers carry most of the story:
- The open, $8.00, is the first price posted, set before much money has been bet. The opening price entry covers what it can and cannot tell you.
- The high, $9.00, is the longest price the runner reached. Here it came early, when the market was thin.
- The low, $5.50, is the shortest, reached 5 minutes before the jump.
- The current price, $6.00, is the only one you can still take, and only if it is on offer when your bet lands.
From open to current, the implied chance rose from 12.5% to 16.7%: 4.2 percentage points, or a third more than at the open (8.00 / 6.00 - 1 = 33.3%). From the high to the low it rose 7.1 points, before easing 1.5 points at the end.
For NSW TAB race meetings, the official price fluctuations have come from Racing NSW's NSW Official Price (NOP) service since May 2017. Racing NSW says the NOP is calculated from the prices of wagering operators offering betting on NSW meetings, including corporate bookmakers and TAB fixed odds (checked October 2026). The same service produces the starting price and the top fluc for those meetings.
Firming, drifting and plunges
A runner is firming when its price shortens, because the market rates its chance higher, and drifting when its price lengthens. A small lengthening, a tick or two, is often called easing. A plunge is firming at its most extreme: a burst of money that cuts a price hard, often late. A drifter is the opposite case, a runner whose price keeps going out.
Not every move is about money for the runner itself. When another runner is scratched late, its share of the market disappears and the prices of those left shorten as the market is re-framed, so a firm straight after a scratching may carry no new money at all.
How big is a move?
Dollars are a poor ruler for a price move. Turn each price into an implied chance, which the odds converter does for any price, and the size of a move looks very different. With illustrative prices:
| Move | Implied chance before and after | Change in chance | Chance up by |
|---|---|---|---|
| $2.00 to $1.80 | 50.0% to 55.6% | +5.6 points | 11.1% |
| $5.00 to $4.00 | 20.0% to 25.0% | +5.0 points | 25.0% |
| $21.00 to $15.00 | 4.8% to 6.7% | +1.9 points | 40.0% |
| $41.00 to $26.00 | 2.4% to 3.8% | +1.4 points | 57.7% |
The working for the third row: 1 / 21.00 = 4.8% and 1 / 15.00 = 6.7%, a rise of 1.9 percentage points, and as a share of where it started, 21.00 / 15.00 - 1 = 40%. A $6 move on an outsider shifts less chance than a 20 cent move on a favourite, yet raises that outsider's chance by a bigger share. Both readings matter: points tell you how much of the market moved, the share tells you how much the market's view of that runner changed.
Moves also have to balance. If a bookmaker's market adds up to 116% and one runner firms from $5.00 to $3.80, its implied chance rises from 20.0% to 26.3%, which is 6.3 points. Unless the bookmaker lets the market's total grow, the other runners must give up 6.3 points between them, so a firmer means drifters elsewhere in the same race.
Bookmaker flucs and exchange movement
A bookmaker's flucs are the prices one bookmaker posted over time, or the prices an official service such as the NSW Official Price gathered from several. The bookmaker sets each price and moves it when money comes in or its view changes, and every price carries the bookmaker's margin. Exchange movement is different. On the Betfair exchange, punters back and lay against each other, and the prices on offer change as punters place, take and cancel offers. The exchange's commission comes out of net winnings rather than being built into the price.
Reading the two side by side tells you more than either alone. With bookmaker and exchange moves in the same window, some possible readings:
| Bookmaker prices | Exchange price | One possible reading |
|---|---|---|
| Firming | Firming | The move is market-wide: money and opinion agree |
| Firming | Steady | Bookmakers have cut on their own bets, so their price may now sit below the exchange |
| Steady | Firming | Bookmaker prices have not caught up, so they may sit above fair until they move |
| Drifting | Firming | Check for a stale price or a data error before reading anything into it |
These are readings to check, not rules. The value betting on horse racing guide shows how to put a number on a gap between a bookmaker price and the exchange.
Risk: Betting involves risk. A bookmaker price that has not caught up with the exchange can be cut before your bet lands, and the exchange can misjudge a runner too. See responsible gambling for limits and support.
Why early markets move more
An early market runs on thin money. The opening price is a bookmaker's estimate before many bets have been struck, so the first money for a runner is also the first real information, and prices react to it. On the exchange, thin means little money waiting at each price, which an illustrative ladder shows:
| Back prices available, with money waiting | A $300 back bet | |
|---|---|---|
| Race morning | $8.00 ($120), $7.80 ($90), $7.60 ($200) | Takes all of $8.00 and $7.80 and $90 at $7.60, an average price of $7.82; the best price left is $7.60 |
| Near the jump | $8.00 ($2,500) | Filled at $8.00; the price does not move |
The average price works out as (120 x 8.00 + 90 x 7.80 + 90 x 7.60) / 300 = $7.82. One $300 bet moved the morning price two steps, which shows in the price history as a firmer; the same bet near the jump left no mark at all. News arrives through the day as well, from scratchings and track rating changes to rider changes, and each item can move a thin market a long way.
So the same size of move has less money behind it early than late. An early price can also be one that never comes back: in the line above, the $9.00 on race morning was gone by late morning. Why betting odds change covers the other things that move a price.
What flucs can and cannot tell you
Flucs can tell you which way money and opinion have gone, whether a move is one bookmaker or the whole market, and whether the price you took beat the final price. Taking $8.00 early on a runner that started at $6.00 beat the close by 8.00 / 6.00 - 1 = 33.3%; taking the $5.50 low was 5.50 / 6.00 - 1 = -8.3% against it. That comparison, closing line value, is a better test of your prices over many bets than a handful of results.
They cannot tell you who is betting or why, how many bets a move took, or whether the runner will win: a heavily backed runner can still be beaten. To find out whether firmers in your own bets did better than their final prices implied, tag them in your records and count them over a few hundred bets.
Risk: Betting involves risk. A firming price is a market opinion, not inside information, and following moves can mean taking a shorter price for the same chance. See responsible gambling for limits and support.
Flucs are price history, top fluc is a payout rule
The two names sound alike and do different jobs. Flucs are the record of where a price has been. Top fluc is a payout rule: a winning bet is paid at the highest fixed price recorded in a betting window, with the window and the price source set by the operator's own terms.
Because the operator sets the window and the price source, the highest number on a fluc line is not always the price a top fluc bet pays: an early peak like the $9.00 above can fall outside the window. For NSW TAB race meetings, Racing NSW says the top fluc is produced through the NSW Official Price service, the same service as the official flucs. Check the terms of any top fluc bet before you rely on a price you saw in a fluc line.
Reading flucs on the Terminal
On the Terminal, a runner's prices across the bookmakers sit with the price history (flucs) for each and Betfair back and lay alongside. You can see whether a move is one bookmaker or the whole market, where each price sits against the exchange, and whether a runner is firming or drifting. The closing lines record the last prices before the jump.
The Terminal covers racing and sports prices from 40+ bookmakers, collected in repeated reads rather than tick by tick. The latest move at a bookmaker may not be on screen yet, so check the price in your bookmaker account before you bet. Betfair is a trade mark of its owner, and B337 is not affiliated with it. Bookmaker names are trade marks of their owners. B337 is not affiliated with them.
The free odds comparison board shows two bookmakers' win and place prices on the next races with their price history, and a free account opens a limited view of the Terminal with live odds. A free account does not show Betfair prices or closing lines; those start at Terminal View, as the pricing page sets out.
Risk: Betting involves risk. Price history shows where a market has been, not where the race will finish. For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au. See responsible gambling for limits and support.