← The +EV course
095 min read

Arbs, and what they're telling you

When two books disagree so badly that both sides are bettable.

Occasionally two books get so far apart on the same market that you can back both sides and come out ahead whichever way it lands. One book has the over at +130 while another has the under at -105. Stake them correctly and both outcomes pay.

SideStakeReturns
Under -105 at Book A$100$195.24
Over +130 at Book B$85$195.50
The price you get+130
Implied
43.5%
Wins on $100
$130
EV
+8.5%

Fair price is +112 (47.2%). At +130 you're being paid as though it were rarer than it is.

The part that matters more

An arb is a flashing light. If the two sides add up to less than 100%, one of those prices is badly mispriced — and that side is a strong +EV bet on its own. You do not have to take both. Reading arbs as a signal rather than a strategy is how most serious bettors use them.

Why it isn't as clean as it looks

  • Lines move in seconds. Get one leg down and watch the other move, and you are holding a negative-EV bet you did not want.
  • A book can void a bet on an obvious error, leaving you with one naked side.
  • It is the fastest way to get limited. Books identify arbers quickly and they are the first accounts closed.
  • Your money sits tied up on both sides for a return of a few percent.

Straight +EV betting makes more money over a season, keeps your accounts alive longer, and leaves you with something to watch. That is the strategy this app is built around — but knowing what an arb looks like tells you where the softest number on the board is.

Check yourselfNothing is scored

1 of 2

You spot a genuine arb. What is it mostly telling you?

2 of 2

What is the biggest practical cost of arbing?

Takeaway

Every arb contains a +EV bet. Take that side and skip the hedge.

+EVergreen

Terms from this lesson

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