If the situation is as stated, you should not need to pay any capital gains tax and you will have a capital loss to carry forward against future gains.
Using hypothetical figures but which should match your situations: If your capital losses from other shares are $10k say and your gains from the takeover are $7K and were held for under a year, then you have no net capital gains for the year. You apply the $10K against the $7K leaving no gains for the year and the $3K loss left over is carried forward to future years when you can deduct it from future gains.
The situation can be fairly complex, particularly if you also have gains from shares held longer than 12 months, but in your case if it is as you stated it is easy enough.
Note that you still have to include the gains and losses in your tax return even if it is not going to effect the tax you pay. This is particularly important to record the carry forward loss which will be a benefit to you in future years. Also, if you ever do have net capital gains, they will be taxed at your marginal tax rate (the gains are added to your other income and then tax is calculated).
