Who wants to copy and paste the usual explanation as to how betting markets get closed on transfer markets?
The TL; DR version is that a few daft twats lumping on hundred quid is often enough.
Aye don’t want to copy paste like you’ve said but there was an article about this about 4-5 years ago that explained that the “transfers betting market” is absolutely minuscule in relative terms. Over the summer it’s worth something daft like £30k to each betting company. Hence why someone throwing £500 on a transfer happening locks the market.
It’s too open to abuse. It takes a lot more to fix a competetive match than for somebody to know a transfer is going through ahead of the press and lay some money on it. Thousands of transfers happen every summer, why would the bookies leave themselves open to people laying money on something they are certain will happen?
They will accept a couple of quid here and there because it’s speculative, who is going to lay £5 on something they are certain of? It’s the big bets they just won’t accept.