Spread betting
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Spread betting is a form of gambling on the outcome of any event where the more accurate the gamble, the more is won and conversely the less accurate the more is lost. A bet is made against a 'spread' (or index), on whether the outcome will be above or below the spread. The amount won or lost depends on the level of the index at the end of the event. The spread represents the index firms' margin.
The concept has a long history in American sports betting and was exported to the United Kingdom in the 1980s. In North America the bettor usually bets that the difference in the scores of two teams will be less than or greater than a value specified by the bookmaker. For example, if a bettor places a bet on an underdog in an American football game when the spread is 3.5 points, he is said to take the points; he will win his bet if the underdog's score plus 3.5 points is greater than the favorite's score. If he had taken the favorite, he would have been giving the points and would win if the favorite's score less 3.5 points was greater than the underdog's score.
Spreads may be specified in half-point fractions to avoid ties, or pushes. The winner of a North American spread bet wins the amount that he has bet, while a losing bettor loses the amount wagered plus the bookmaker's commission, which is commonly known as the vigorish or vig, and is usually 10 percent of the original wager; in the United Kingdom both sides are held at odds of 9-10. In North American betting a push is treated as if no bet at all had been made, while in the United Kingdom "dead heat" rules apply, resulting in a net loss of £5 on a £100 wager due to the 9-10 odds of the proposition.
If a key player on a side is marginally injured and may or may not play, the "sports book" — or establishment that handles the bets — may declare the game off-limits to bettors (by not quoting any spread at all on it), or may "circle" the game; in the latter scenario, lower maximum amounts for each bet are enforced (typically $5,000 instead of the $25,000 limit observed at most Las Vegas sports books) and certain specialty wagers, such as "teasers," are banned on either side in the game. (A "teaser" is a bet that alters the spread in the bettor's favor by a predetermined margin, often six points - for example, if the line is 3.5 points and the bettor wants to place a "teaser" bet on the underdog, he takes 9.5 points instead; a teaser bet on the favourite would mean that the bettor takes 2.5 points instead of having to give the 3.5. In return for the additional points, the payout if the bettor wins is less than even money. At some establishments, the "reverse teaser" also exists, which alters the spread against the bettor, who gets paid off at more than even money if the bet wins.)
In the United Kingdom spread betting has come to resemble the futures market. The bets are usually on the outcome of sporting events or indeed on financial instruments, but the firms often offer bets on more arbitrary events - such as the number of corners during a football match or the total shirt numbers of the goal scorers.
Unlike fixed odds betting the amount won or lost can be very large, as there is no single stake to limit the maximum losses. However, it is usually possible to place a "stop loss" with the bookmaker, automatically closing the bet if the value of the spread moves against the better by a specified amount. "Stop wins" are the opposite -- closing the bet when the spread moves in a better's favor by a specified amount.
Example: In a soccer match between Liverpool and Everton the spread for corners is 12-13, the index firm believes there will be 12 or 13 corners in total during the match. A bettor approaches the firm with the belief that there will be more than 13 corners during the game, the bettor 'buys' at £25 a point at 13. If the final total of corners is 16 the bettor has won, receiving 3 x £25. If the final total of corners is 10, the bettor loses 3 x £25. A 'sell' transaction is similar except made against the bottom value of the spread. Often there is live pricing, which changes the spread during the course of an event allowing a profit to be increased or a loss minimized.
In North American sports betting many of these wagers would be classified as over-under (or, more commonly today, total) bets rather than spread bets. However, these are for one side or another of a total only, and do not increase the amount won or lost as the actual moves away from the bookmaker's prediction. Instead, over-under or total bets are handled much like point-spread bets on a team, with the usual 10% commission applied. Many Nevada sports books will allow these bets to be used in parlays, just like team point-spread bets, making it possible to bet, for instance, "the Packers and the over," and be paid if both the Packers "cover" the point spread and the total score is higher than the book's prediction. (Such parlays usually pay off at odds of 13:5 with no "vig," just as a standard two-team parlay would.)
The mathematical analysis of spreads and spread betting is a large and growing subject. For example, sports which have simple 1 point scoring systems (e.g. baseball, hockey, and soccer) may be analysed using Poisson and Skellam statistics.
