Sputnik spoke with Ladbrokes' head of PR, Alex Donohue, who said that political betting has grown massively in recent years, especially since the Scottish independence referendum in 2014.
"We think [the EU] referendum will be the biggest political betting event of all time, we think across the industry there could be anything up to USD$146 million (£100 million) riding on the outcome of the vote on Thursday, so it's a pretty big deal for us."
"Polling and betting are two very separate things — a poll is a snapshot of voter intention on any given day, or given moment, it represents the opinion of a very small sample size at a given point on how they intend to vote. Betting is all about predictions — it's about people taking money out of their pockets and placing a bet on a prediction about what they think will happen in the future," he added.
According to Alex, the best time to have placed a bet on the EU referendum would have been about a week ago — as the closer we get to the vote, the narrower the odds have become.
High profile EU referendum bets include that of UKIP leader Nigel Farage — who placed USD $1,468 (£1000 ) on Leave — and only last week, a betting shop in London received a massive USD $51,390 (£35,000) bet on Remain.
Close though the odds might be, Alex Donohue told Sputnik that the smart money is on a Remain vote — which he says looks around 75% likely, compared to a 25% likelihood of a Leave:
"If you were to put USD$147 (£100) on Leave — and it was a Leave — you'd win USD$440 (£300). If you were to put [the same] on Remain at the moment, you'd win USD$37 (£25) plus your stake. So that gives you a sense of how the odds definitely favour a Remain. I think if you had a spare USD$1,468 (£1000) lying around, and you put it on Remain, then you would win £250 [USD $367]."
UK citizens will vote on June 23 in a referendum on the country's EU membership.