Level 3 · Sharp

Steam and market makers

Lesson 4 of 7 · 4 min read

Prices don't appear from nowhere, and they don't move at random. A handful of books do most of the work of finding the right number, and most of the rest follow. Knowing which is which is how you read a line move.

Market makers and followers

A market maker posts a price, takes large bets against it and moves the number on what it learns. Pinnacle and Circa are the best-known examples; offshore books like BetOnline and Bookmaker also move early and take sharp money. That is book sharpness: leading price discovery, not just charging less vig. Most US retail books, DraftKings and FanDuel included, work differently. They set prices largely off the leaders, shade them for their own customers and limit bettors who win. So when a line moves, the first question is where the move started.

Steam versus a single book correcting

A steam move is a quick, same-direction move at several sharp books at once. It usually means respected money hit the same side in several places, or news broke. A single book moving alone is different: often it is correcting its own stale line, catching up to a market that already moved. Steam is information; a lone correction usually isn't.

Our steam detector applies the same tests any careful reader of steam uses. Did more than one independent sharp operator move? Did they move the same way, by a meaningful amount, within minutes of each other? Two books owned by one company count as one operator, because a company can't confirm itself. And on a spread, a move is weighted by the key numbers: a half-point through 3 means far more than one through 9 (see Key numbers). The record is public at /trust/steam.

Chasing steam

By the time you hear about steam, the sharp books have already moved. Any value left sits at books that haven't caught up yet, and it rarely lasts. Betting the new number at a book that has already moved is paying the price the professionals created, not beating it. Closing line value tells you which side of that you are on: if you are reliably early, you beat the close.

Reverse line movement and public splits

Reverse line movement (RLM) is a line moving against the side most bettors are on: 75% of tickets on the favorite, and the number drops anyway. The classic reading is that fewer, bigger, sharper bets are on the other side. It is a fair idea with a weak input. Public betting percentages come from the few books and apps that publish their own; nobody sees the whole market, ticket counts ignore bet size, and one book's split says little about the money that moved Pinnacle. That is why we infer professional action from what actually moves prices, fast same-direction moves at sharp books, rather than from public splits.

Example. A Sunday 1 p.m. game, Lions moneyline (illustrative prices, not live data).

Time	Book	Move	Implied chance
11:02	Pinnacle	−150 to −165	60.00% to 62.26%
11:04	BetOnline	−150 to −165	60.00% to 62.26%
11:20	A retail book	still −150	60.00%

−150 implies 150 ÷ 250 = 60.00% and −165 implies 165 ÷ 265 = 62.26%, a move of 2.26 points. Two sharp operators moved the same way by a meaningful amount within minutes, so this is steam. The retail book's −150 is now stale: if your number for the Lions agrees with the new market, that is the price to look at, and it may not last.

Compare Wednesday: BetOnline moves the Lions from −140 to −150 while Pinnacle has sat at −150 since Monday. One operator moving alone is not a quorum, and a move toward a price the market already set is a correction, not steam. And if a second book owned by the same company moved with BetOnline, that would still be one operator.

Key takeaway. A move that starts at several sharp books at once is information and a lone book catching up usually isn't, so judge a line move by where it started and judge your timing by CLV.

Terms in this lesson

Steam Move Book Sharpness Sharp Money Stale Line Line Movement Reverse Line Movement Closing Line Value Offshore Book