During the year I sold off some dot bomb shares at a loss, can I write this off against my taxes or do I need to have gains from the sale of shares to do that?
Thanks

Tax Topic 409 would seem to address your question.

In short, it seems to say that you can write off up to $3000 ($1500 if married filing separately) in capital losses, with any more able to be held over for later year(s). You have to add all your capital gains and losses together, though, so if you lost $2000 with the dot-bomb stocks but got $2000 from other stocks, then you don't get any capital loss advantage, but you probably won't have to pay any taxes on the amount you gained, either, as they add up to zero.

Thanks Bitt.

ISTR that's what they said in my accounting class a couple years ago too.