# 19/04/2022

### 1. Greyhound downtrends

A clear downtrend on a BFCharts graph in the last traded price of the dog with the highest matched volume a few secs before the off.

The first part of the video was taken right before the beginning of a race.

The second part was first recorded at 2 mins before the off, and then a few seconds. The dogs with the highest matched volume showed a downtrend in their last traded price.

### 2. Lay-Dutching tennis players

Laying two or more selections at a price *below 2.0* in a Win market will bring you guaranteed profit. As simple as that!

This is especially obvious in tennis markets where prices may jump up and down as players win or lose their games.

To take advantage of this volatility, place Dutching lay bets at 15-20 ticks below the current price and wait for the bets to get matched.

Here is the Market Locator search template you need for finding tennis markets with a narrow price gap between the players:

### 3. Laying all horses at < 2.0

Elaborating further on the topic of laying below 2.0.

The same trick will work with horses, only here it is easier to lay the entire field at a chosen price. The lower the price, the higher is your profit, however, the lower still is the probability that both horses will arrive at that price. This can only happen if some horse gets ahead of an obvious favourite closer to the end of the race.

How can you quickly lay on all horses? The easiest way is to switch to the Engineer mode and place all bets with one button.

Even if only one of them gets matched, your losses will be moderate due to the low price: with a bet at 1.2, it is only 20% of your initial bet size.

If two or more are matched on the other hand, the result is in the video attached! :)

### 4. Cross-matching in football markets

Why does it make no sense to look for arbitrage opportunities across markets of the same event?

Because BetFair has long been tracking such opportunities and adjusting prices on the fly.

Let's look at a simple example in football.

Selection "0 - 0" in "Correct Score" is equivalent to "Under 0.5 goals" in "Over/Under 0.5 goals".

You'd think it would be easy to back on "0 - 0" and lay on "Under 0.5" or vice versa, to generate some guaranteed profit. If only the prices were right...

Well, guess what?

They are NEVER going to be right. If you look at the screenshot, you will see that the back price of any of these two selections is never higher than the lay price.

And even if they were just occasionally, keep in mind the commission that is charged on profit in each market separately. The commission would eat out anything you'd gain from the arbitrage.

The exchange has been running an algorithm of automated price adjustment to prevent price imbalance across the markets of the same event. The algorithm is called "cross-matching", and you can google its details.

Here’s a more complicated cross-market betting case.

The Under 1.5 goals in “Over/Under 1.5 goals” corresponds to three selections in “Correct Score”: "0 - 0", "0 - 1" and "1 - 0".

In order to execute an arbitrage, you need to back on all three of those Correct Score selections and lay on Under 1.5.

But is there an arbitrage opportunity at all? From the previous case, you should have guessed already that there isn’t.

Let’s calculate the combined odds of Correct Score selections using their probabilities (see the screenshot). It turns out that their back odds are way lower than the lay price of Under 1.5, so it makes no sense to bet on them (yet at a first glance it looks like a super sophisticated strategy!).

If you don’t take anything at face value, you can even place those bets after all and make sure that the profit in any of the markets does not cover the liability in the other.

So if anyone sells you this strategy as a profitable one, don’t ever fall for that. Cross-matching will always be on guard!

And if you are wondering what that magic formula is we used to calculate the combined odds in the previous post, here it is:

`Equivalent price = (100 - book)/book + 1`

Where book is the sum of the chances to win (100/price) of all the selections involved in the Dutching.

### 5. Quick formula for a trade-out bet for a selection with multiple mixed bets

Here’s a quick formula for a single trade-out bet that equalises profit/loss from a bunch of back and lay bets on the same selection.

Suppose you have clicked away at betting buttons (or maybe used triggers) and ended up with 3 back bets and 2 lay bets, all with different sizes and prices. It does not matter how this has happened: either a wrong choice of market or some bets did not match as expected, and now there is very little time to ponder as the market is In-Play.

Use this step-by-step algorithm:

1. Multiple the price of each bet by its size.

2. Add up the results (they are called payouts) separately for BACK and LAY.

3. Find the lesser sum and place a bet of that type. Take a look at the screenshot:

the back payout is 27.38, while the lay payout is 21.28. Therefore, we need to LAY, since the lay payout is less than the back one.

4. The bet size will be equal to the difference between the payouts divided by the selection’s current price (in the example above, the current price is 1.92). In our case, (27.38 – 21.28) = 6.1. Divide 6.1/1.92 = 3.18.

5. Lay £3.18 at 1.92.

P.S.

Or you can ditch the calculator and place the same bet with just one click using MarketFeeder’s Betting Interface.

### 6. Price drops at volume spikes

Take look at these BetFair graphs:

There is an interesting picture of last traded price drops around the moments when a substantial amount of money gets matched on the selection.

Gives you ideas for trading strategies...