Ann: Operations Update, page-88

Rails, I can only comment on NZ tax law. For us your scenario depends upon whether you are seen as an investor or trader in shares. An investor is out of luck. A trader on the other hand can claim the cost of the shares in the year purchased. Any future sales are taxed at personal or company tax rates depending on your trading structure.
A trader as defined under tax law is quite different to what we think of a share trader to be. We tend to think of someone who is in and out of shares often. They would be considered a trader but anyone buying a stock that has no foreseeable dividend stream and holds for along time is also a trader as tax law holds you have bought the shares for capital gain. So generally by buying a speccie regardless of holding time you are a trader and therefore able to claim your purchase cost. In the case of the company folding you simply do not have a sale to report so the purchase cost holds as a loss.
Of course the tax department will review on a case by case basis as trading verses investing can be as clear as mud at times.