bhp off market buyback more clarification

Terms are very similar to the buyback of this time last year.
Once again the Buyback is heavily tax driven and the outcome is heavily dependent on the individual's tax position.

The question for the moment is:

As a non holder of BHP shares should I buy on the market with the intention of selling into the buyback?

The "window" for purchase is today Wednesday and tomorrow Thursday. If purchases are made after Thursday, the purchase does not meet the 45 day rule and the strategy fails in all cases.

On the assumption that the purchase price today is the same as the price on which the buyback price is calculated (End of March) before the discount is applied, the outcomes are as follows:-

Zero tax payers - 20% after tax profit on gross purchase price
15% tax payers - 15% after tax profit if capital loss can be offset against current year capital gains that would otherwise pay full tax. If capital loss can only be offset against discounted capital gains, then the figure is 11%

31.5% tax payers 9.3%, minus 2.6% respectively
46.5% tax payers 4.2%, minus 13.5% respectively

The really critical question is how the purchase price today and tomorrow relates to the price at the end of March. The buyback will be heavily bought and there is a distinct possibility of a slump back to more normal prices once the "window" for purchase has closed.

The other issue is the degree of scaleback, which also will mitigate against the 31.5% and above tax payers.

So in my view the profit margin for tax payers over 15% is not sufficient to justify this risk of a significant fall of BHP on Friday, which continues until end March. So my view would be that Superfunds both tax paying and non tax paying should buy to sell back, others shouldn't.