Comment by slg
1 day ago
>Bookmakers price purely based on facts and statistics. Their pricing isn't affected by excitement nor by how many people are betting a certain way.
If this were true, lines would never move unless there was breaking news, but we see lines move all the time without there being any material change to those "facts and statistics".
> without there being any material change
Without there being any material change you can see. If you had access to all the tips and data and insider information that sportbooks operate with, you could be a bookmaker too.
>If you had access to all the tips and data and insider information that sportbooks operate with
Can you give an example of what you're talking about here? Because it sounds like you're accusing these large publicly trade companies of participating in organized crime. There is regulation when it comes to sports betting that doesn't exist with general prediction markets. An athlete can't just feed a sportsbook "insider information" in the way you're suggesting. The only private info that they are supposed to have is better behavior details that you claim doesn't factor into their decisions.
Books like DraftKings and FanDuel get their lines from market makers like Circa. Market makers use a variety of information for setting initial lines (you'll have to go ask them), but one of the main ways they move lines afterwards is professional action. That is, if some person or entity who Circa knows to be a profitable professional better puts down a large bet in a certain direction, Circa will move their line in that direction.
Where did that entity get that information, and how are they right so often? Your guess is as good as mine. I'm not accusing anyone of anything.
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I think the distinction is that sports betting companies are basically casinos, need to guard their edge, and although they will tolerate some moving of lines, they will kick out players who consistently eat their edge, and will rig the lines at a place where they can still profit.
Different from a prediction market like Polymarket or Kalshi whose income probably comes mostly from transaction fees rather than house edge. Otherwise these platforms wouldn't welcome bots so much. Bots => efficient pricing + transaction volume => profit for them
The sustainability of prediction markets depends heavily on continuous liquidity provision - without bots and market makers, spreads would widen and user experience would degrade quickly
These are all reasons supporting my point as they would make sports betting platforms less efficient meaning it would be easier to find arbitrage in their prices (at least temporarily, until you're booted for being too successful).