The beauty of this strategy is also:
- one does just 1 trade in 2.7 months... ;-) (maximally 2 trades if the stop gets hit).
- to get stopped-out is very unrealistic because of the big cushion of 10% calculated-in.
- a fix profit of 9.42% in 2.7 months (annualized 49.2%) as long as the stock doesn't fall more than 10%.
- the profit (ie. the credit) is received immediately when opening the position.
(but this is of course the "unrealised profit" up-front; only after the expiration date it becomes "realised profit").
- the own account (excluding the credit) is protected by the 10% stop level, ie. is risk-free under normal market conditions.
- ...
Of course in reality one would do many such trades with different stocks in parallel to apply diversification.
PS: the annualised profit has to be reduced by the interest paid for the margin. For example at the broker IB the interest paid for margin is 1.87% p.a.
That means we have to subtract that from the 49.2% above, giving us a net annualised profit of 47.33%.
Minor correction:
Since the margin makes up only 4/5, the net annualised profit then makes 49.2 - 1.87 * 4/5 = 47.70%