This conundrum has no definitive answer. Diverse members in the organization share different levels of responsibility, based on the magnitude of the transition, the goals it is expected to accomplish, and the technology they implement.
Historically, the CIO has driven all IT technology improvements programs. But now, it is not just the obligation of the CIO. The CEO plays a rising function in the policy development and implementation of technology programs across the organization. Nascent positions, such as Chief Digital Officer, Chief Technology Officer, and the Chief Innovation Officer, also play a factor.