It sounds like the sales reported on your Form 1099-B may be from an Employee Stock Purchase Plan (ESPP). Tax treatment on the sale of ESPP stock is differently, based on how long you’ve held the shares. In order to receive beneficial tax treatment given under Section 423 for your ESPP, you are required to hold the shares:
If shares are sold after the required holding periods, it is considered a qualifying disposition and is eligible for the beneficial tax treatment. If shares are sold before the required
holding periods, it is considered a disqualifying disposition and is not eligible for the beneficial tax treatment.
If company stock was not involved, more information about the Form 1099-B and the sales transactions is needed to determine what the qualifying disposition column is referring to.