Good question. But I don't know. And I'm assuming you mean if you buy btc at price 'X', then the price drops and you sell out for a loss.

...hmmmm...

You can with stocks and forex trading. But let's a assume worse case that this is not like either of those.

Seems almost as if you don't have at least claim a home business you are operating under, it might be difficult to categorize the loss. But I'm not sure.

..............

Here's a scenario:

Assume the following under two circumstances:
either a home business model and as just individual speculation.

1. You mine bitcoins.

2. You sell them on an exchange. (effective gain)

3. You keep the money in the exchange, and buy bitcoins again to trade.

4. You sell those at a lower price. (effective loss)

Can you deduct (4) from (2) under either circumstance?
Ifso, which one and how?
If not, then in what other circumstance could it be deducted?