DaveJB said:
Hehehe, remember we let them build a wall to stop the sassenachs treading on the heather
😎
The only 'personal' thing about position sizing is knowing how much cash you are prepared to blow if things get really bad (emergency stop).
Say you had £10,000 (obviously petty cash to you, Dave)
You decide that you are prepared to place a maximum of £2500 per position and were prepared to loses a maximum of £250 against your '****, get me outta here' position - as opposed to a more gentlemanly scramble for the door if things just don't look right. So, you are prepared to hold 25% of total capital in any one position and prepared to risk 2.5% at any one time.
For arguments sake consider the following targeted trade:
Trading at 105 having just broken a double bottom at 100 from 70, giving you a target of 130. You note the major support at 85 and a reaction low at 80.
Your initial plan for the trade is to buy at 105 with a controlled exit if the price closes below 85 and an emergency exit at 79. Target 130.
The maths:
The total travel you are prepared to put up with is 105-79=29 points. The maximum cash you are prepared to lose is £250, less dealing costs (for arguments sake £15). So the maximum amount of shares you can buy against your maximum pain is (250-15)/0.29 = 810 shares.
Buying 810 shares at the current price would cost £850.5 - well within your maximum of £2500 per position.
Your targeted exit is 130 so your profit should it be hit is 25 per share - £202.5 - less the pleasure - £187.50.
As this stands some may take the deal, others not as the risk/reward ratio is less than 1:1 - you are risking £250 to make £187.50 - again we are back to personal choice.
As the trade progresses - assuming it goes up! The stops can be moved accordingly - say the price gets to 115, some may decide to lift the initial stop to 100 and the emergency stop to 90. If you are wanting to live with purely % stops, then just alter the figures accordingly.
That just saved you the cost of a book
😉
Of course Mr Van Tharp is famous for his position sizing, which is why he gave all his pension money to one guy - who then defrauded him of the lot. (allegedly/apparently etc...)