What type of stock bonus was this? Do you still have the stock?
So it appears they withheld income tax upon issuance of the shares. The income, and tax withheld, will be reported on your W2 next year. You basis in the stock will be the amount you recognized as ordinary income on the W2. Please let me know if you have further questions.
Any gain or loss will be calculated based off of the difference in selling price and the amount you recognized when vested. These would be either capital gains or capital losses. Please note that the income taxes withheld were for the W2 income portion only. Any capital gains would be subject to further tax. Please let me know if you have further questions.