Arbs › Guides › Closing line value: why it predicts long-term profit
Closing line value (CLV)
Arbs research desk · Updated 2026-11-01 · Reviewed 2026-11-01 · 2 min read
The short answer: Closing line value is how much better your price was than the market’s last price before the game. If you bought at 45¢ and it closed at 50¢, you beat the close by 5 points. Bettors who beat the close consistently tend to win over time.
Why the close matters
The closing price has absorbed the most information: injuries, lineups, weather and the sharpest money. It is the best public estimate of the true probability. Buying below it means you paid less than the outcome was worth by the market’s final estimate.
How to measure it
On Polymarket, compare prices directly. At a book, compare your odds with the closing line after its vig is removed:
CLV in points = closing price − entry price; CLV in % = your decimal odds × fair closing probability − 1
Worked example: Polymarket: bought at 45¢, closed at 50¢
- CLV: 50 − 45 = +5 points
- With the fee, your cost was 46.24¢
- Value at the close: 0.50 ÷ 0.4624 − 1
+8.1% against the closing price.
Worked example: Sportsbook: bet +110, closed −105 / −115
- Implied at the close: 51.2% and 53.5%, a total of 104.7%
- Fair closing probability for your side: 51.2 ÷ 104.7 = 48.9%
- CLV: 2.10 × 0.489 − 1
+2.7%: you got a better price than the market settled on.
Average it over every bet, not just the winners.
Why it beats win rate as a check
Win–loss records need thousands of bets before luck washes out. At even money a single result swings by about one unit, so to show a 2% edge at two standard errors you need roughly:
n ≈ (2 × σ ÷ edge)² = (2 × 1 ÷ 0.02)² = 10,000 bets
CLV gives a reading on every bet whether it wins or loses, and it varies far less than a result does, so the same evidence arrives after a much smaller sample. Arbs reports average CLV on its locked picks on the track record.
Pitfalls
- Use the true close, the last price before the start, not a price after kickoff
- Thin markets can close on one stray trade; prefer the midpoint over the last trade
- Remove the vig before comparing book prices, or every bet looks worse than it was
Frequently asked questions
What is good CLV?
Any consistent positive average is a good sign. Beating the close by 1–2% on average in major markets is strong.
Can I win without beating the close?
Over a short run, yes. Over a long run it is rare.
Does Arbs track CLV?
Yes. Every pick is locked before kickoff, and the record shows how its entry price compared with the close.