very interesting (to me).it's very rare but it does happen. found a 1995 column by Andrew Beyer claiming you can guarantee a win in a minus show pool when the big horse has 96.6% (my calculation) of the money in the pool bet on it.
a couple of points:
because of the change to net pool pricing from standard pool pricing when the article was written the bettor gains. in Beyer's article the other 2 horses only paid $2.10 when the big horse showed. Bellafina created a minus pool at Santa Anita on 2/9, she showed and the other 2 horses paid $2.40 and $3.20 because of net pool pricing.
But the more interesting point is that Beyer is actually wrong. You can't guarantee a win because if 2 horses are longshots in the show pool and they don't come in you may not have a profit. Unless you could make some pretty difficult calculations from looking at the totals in the show pools very late, and make different size bets on the entries and they still might not be 100% accurate.
here is his formula:
"While the big plungers load up on a horse such as Cigar, they create the chance for other players to guarantee a profit in the same race. Anyone who seeks to do so must understand how to calculate show payoffs:
1. From the total show pool, first deduct the track's "takeout" -- which in New York is 15 percent.
2. Subtract from the remainder the total amount of money bet on the first three finishers. What is left is the profit that will be paid to winning ticket holders.
3. Divide this figure by three. This is the amount that will be distributed in profit to ticket holders on each of the top three finishers.
4. To calculate each horse's odds in the show pool, divide the amount bet on him into the figure in Step 3.
Suppose, for simplicity's sake, that in a six-horse field the show betting looks like this:
* Cigar $1,450,000
* Horse A $10,000
* Horse B $10,000
* Horse C $10,000
* Horse D $10,000
* Horse E $10,000
* Total pool $1,500,000.
We start by subtracting the track's 15 percent takeout from the total pool, which leaves $1,275,000. If Cigar finishes in the money, there won't be enough money in the pot to pay all the winners, so the track has to make up the difference -- what is called a minus pool. Therefore, each horse returns the minimum $2.10.
But what if Cigar finishes out of the money, with A, B and C running 1-2-3? We subtract the $30,000 bet on them from $1,275,000, leaving $1,245,000.
Dividing this figure by three, we find that $415,000 will be paid in profit to the bettors on each of the top three finishers.
We divide the $10,000 bet on an individual horse into the $415,000, and find that the horse will pay odds of 41.5 to 1 in the show pool. A single ticket returns a profit of $83 for $2, plus the original $2 bet -- a whopping $85 show price.
If we bet $2 to show on Cigar's five rivals in this example, we would invest $10 and collect three $85 show payoffs -- a net profit of $245 if Cigar finishes out of the money. By betting just a little bit less than this amount on Cigar, we will have a profit no matter what happens. Suppose we play the race this way:
* Cigar $230
* Horse A $2
* Horse B $2
* Horse C $2
* Horse D $2
* Horse E $2
* Total $240. If Cigar finishes in the money, we collect our wager on him plus 5 percent, or $241.50. We also get a pair of $2.10 payoffs on the other top two finishers, for a total return of $245.70. That's a profit of more than 2 percent on our investment. If the favorite finishes out of the money, we do even better. This may not sound exciting, but when U.S. treasury bonds are paying annual interest of less than 6 percent, there is nothing wrong with making a certain 2 or 3 percent in a few hours."
https://www.washingtonpost.com/archi...=.5fa8e6046615
