If you were living in MA the entire time between the ESPP grant date and the acquisition date, then 100% of the ordinary income from the sale of the ESPP shares is taxable by MA. That income is directly related to your employment, and if you were working in MA the entire time, it is all MA sourced income. If you moved during that period then it is prorated based on your number of workdays in MA to the total number of workdays during the period. Your long-term capital gains are not taxable by MA.