Did the sale show up on the W-2 and the again on the 1099-B from the broker in the same tax year ? If so you need to adjust the cost basis on the 1099-B to reflect the taxes paid on the W-2. Your employer should have provided the cost basis for you if the broker doesn't have the correct information. Usually the 1099-B will show a loss in the amount of the broker's fee if it is done correctly.
