If all of your stock transactions are included as income in box 1 of your W-2, then you do not need to file Schedule D.
If this plan was a non-qualified plan, then the gains from stock transactions are treated like ordinary income. They are reported in box 1 of your W-2 and taxed the same as your wages.
A qualified stock purchase plan allows the gains from the sale of company stock to receive capital gains treatment, which would be reported on Schedule D.
This
article explains more about Employee Stock Purchase Plans.
