Since this situation happens relatively often, you would think that OFCCP and VETS and EEOC would have a stock answer for this question. However, I'm afraid that the agencies haven't really addressed this in an effective way. Thus, I would suggest that you have the discretion to treat this situation in whatever way makes the most sense to you. As an aside, my sense is that most companies treat individuals who are part of an acquisition as hires for most affirmative action and equal opportunity record-keeping purposes. That doesn't mean there aren't other approaches to consider, though. This situation may be made somewhat more complicated by the fact that your HR system of record may show the hire date for persons who were part of an acquisition as the date they joined the acquired company rather than the date they joined your company. Conversely, this may give you a reason to treat the individuals who were part of the acquisition as something other than a hire.