How is SP (starting price) stake calculated?

[seale]

I had a bet place via excel which stated:

£ 11.97 Lay bet placed on Killfinnan Castle at 4.3. Entirely unmatched when it initially reached the market

I also used the global command: "Take_SP_All".

The final amount actually matched with the SP was:
£ 10.31 Lay on Killfinnan Castle at 4.81.

The lay amount is different?
Is this due to SP being based on liability not stake. Does BetAngel adjust the stake to limit the liability?

Any help would be appreciated.

[MarketTrader]

Bet Angel just submits the bet to the exchange. It doesn't know what the SP will be in advance and cannot adjust the stake accordingly.

The exchange sets the SP.

http://promo.betfair.com/betfairsp/FAQs_theBasics.html

[seale]

Managed to work it out by myself.

Based on the bet made within Bet Angel (at a set stake and amount) an expected liability is made.

When SP is taken, the stake gets amended to keep the same max liability.

This is due to SP being based on specifying liability rather than stake.
Even though my initial bet was for a fixed stake, it gets amended based on the fixed liability rules.

[SpikeyBob]

That's pretty cool, I never knew it worked like that tbh. I may start using it if it adjusts the stake to only maintain the same liability. Does that mean that it would effectively red/green up evenly for you or is the liability still different on that selection?

Cheers

SB

[meadert]

I just got caught out on this today. I placed a back bet for £50, then the offset bet was placed at 20 ticks away. I amended the lay bet to "take SP" as I had to go out this afternoon.

My horse came in slightly, although not 20 ticks, but then I find that my stake was adjusted on the lay bet to be much less than £50. the horse didn't win and neither did I. Seems bl*****y useless to me

[Zenyatta]

No it really is cool. The net effect of 'Take SP' is to convert your trade into a smaller punt at the off, if your trade didn't succeed. So it's actually just like a hybrid of trading/punting! That's the cool thing.

For example, if you placed a 20-tick offset lay trade with 10% of your bank, then applied 'Take SP' and the price had not changed by the off, the net effect of converting to SP would be to convert your lay trade into a standard lay punt with about 5% of bank exposed.

In the case you mention meadert, the price of your selection didn't shorten enough, so 'Take SP' had the effect of converting your back trade into a smaller back punt at the off.

That's my interpretation of it anyway.

[Euler]

You don't know what the strike price will be so you can't use it to trade out as it is fairly likely to be uneven. But it's a useful way of getting a guaranteed exit.

[Zenyatta]

You don't know what the strike price will be so you can't use it to trade out as it is fairly likely to be uneven. But it's a useful way of getting a guaranteed exit.

Well, with 'Take SP', there's usually a small amount left exposed to the In-Play, that's why I say it's seems like a hybrid of trading and punting?

Definitely good for disaster insurance, saved me a couple of times yesterday when the website crashed. And, when you don't know exactly when the start of the race is, you know 'Take SP' will exit exactly on the off, and you can trade out then with the 'Green All'.