You may, or may not need to report the stock sales, depending on circumstances.
If the sales were made some time after the vesting date then you will receive a 1099-B, and you will need to report the sales. Understand that the basis reported on the 1099-B will almost certainly be $0, which is not correct. Your per share basis is the same as the per share "fair market value" used by your employer to calculate the compensation received: GROSS number of shares received x per share FMV.
If the sales were "same day" sales - stock sold simultaneously with the vesting - then you may or may not receive a 1099-B. If you do receive a 1099-B then you certainly will have to report the sale; the typical "same day" sale results in a small loss due to selling commissions and fees. If you don't receive a 1099-B then you don't have to report the sale, though you may want to, just to recognize the small loss.
