A warrant gives the holder a right at a certain period of time to subscribe for new issued stock in the company.
A warrant is normally classified as a security. The assignment is taxed as ordinary income and the subsequent sale will be taxed as capital gain.
An exercise of the warrant to buy shares does not result in any taxation. The sale of the share or the warrant will be taxed as capital gain.
A non-exercised warrant is deductable from capital gain. In these cases the value of the gain is 0 SEK. The costs are premium paid together with the value of the taxed benefit, if any.