Book% Arbitrages or Dutching – aka Over Round

If you trade at online exchange for some time you are probably aware of the term “book percentage”. Not going too deep into explanations I’ll say that it is the sum of the winning chances of each selection. For instance if a runner’s price is 4.4 its chance of winning is 100/4.4 = 22.73.

When book% on the back side is less than 100% you can back on all runners at once at the current odds offered and earn profit no matter who wins. On the contrary, if book% on the lay side is > 100% then you better speed up and lay on all runners.

See example of book percentage calculation below:

Example of book%

Normally – like everything too good – these conditions are unreachable. Usually back book% is strongly above 100% and lay book% is below 100%. But several times during the day you may be lucky enough to encounter such situation. In case book% on the back side is <100% it's called under round - or lay book % increases up to over 100% - then it's called over round. And here’s where MarketFeeder Pro will act much faster than you would do on your own.

Of course bet amounts must be calculated according to the prices available. To know how much you must bet on a selection you must divide payout by the selection's price. The payout depends on the maximum amount you're prepared to spend on all the selections. It equals to maximum/(book %/100). Below is the example of these calculations applied to the previous price table:

Example of book payout

You can see that the maximum amount you'll spend is 500 GBP, whereas payout is 500/1.023 = 488.434 GBP.

If you lay on all selections according to the scheme we offered you will win 11.57 GBP regardless of the outcome of the event. 11.57 is payout*(book% - 100)/100. This way you can see that the bigger is over/under round the bigger will be your winnings.

From now on we will refer to the maximum amount you want to spend as "Maximum Payout" unlike just "payout" which will mean the value explained above.

The term “book” in MarketFeeder Pro means a set of bets placed when a book% arbitrage opportunity is found. MarketFeeder Pro performs all aforesaid calculations automatically and places all the bets simultaneously as soon as it finds over/under round in the markets you have listed. Take a look at the screenshot below:

Book Table

The Excel workbook generated by MarketFeeder Pro includes a special sheet named "booking (arbitrage)" that contains a table of book % arbs. You can add so called "books" to the table and consider them pieces of conditional betting procedures. A book can have its options but generally it's a command to MarketFeeder Pro to bet on all selections in the specified market as soon as there is a sufficient profit guaranteed. Let's speculate on each column in the table:

  • Book Type - can be either "back" or "lay". Defines the type of the bets you want to be made. Accordingly it determines whether MarketFeeder Pro will search for under or over round. Sometimes you may want to search books only on the back side, because if you lay all selections one or more of them may later be withdrawn and you'll lose your money.
  • Min Percentage - specifies the minimum difference between over/under round and 100% at which the book will be traded. Example: if Min Percentage is 0.2, the book will be triggered only when over round will be >=100.2% or under round <=99.8%
  • Market - select the market from the drop-down list.
  • Max Payout - the maximum amount you want to spend per one book (see above) Active – the indicator of the book’s being active or not.
  • Current Book - this column is filled automatically based on your settings. It shows current book% for the specified market (either back - if you keyed in "back" in "Book Type" or lay). The figure will keep changing over time - it is a reference to the appropriate cell on the market sheet belonging to that event.

Once a book is found and nothing prevents it from being traded MarketFeeder Pro will calculate the required bet amounts, place all the bets and highlight the corresponding row in yellow colour.

Book is found and traded

So if a book row in the table has flashed yellow it means MarketFeeder Pro has just placed the bets and you may watch them on the market sheet. As an indicator of a successful result you will see profit/loss column turn all green - positive figures will be showing in each selection's row:

Profit all over the market!

On the screenshot you can see the results of betting with maximum payout of 100 on 12 selections. "Matched" colum show how much was bet on each selection - though the bet amounts are different the profit generated is equal to £0.5 everywhere. Increase your payout - and you will be making much more in one step!

Finally, here’s a tip: with MarketFeeder Pro you can limit the number of selections showing in the market and increase the possibility of finding back under round. If there are some selections that are priced 100 and higher there is chance that they won’t win the race so you can omit them and back only on potential winners.

Learn more about MarketFeeder Pro!