Launched in Oct 2018, EC2 On-Demand Capacity Reservations let you reserve EC2 capacity for any duration. Once you create a Capacity Reservation, the EC2 capacity is held for you regardless of whether you run the instances or not. Until now, Capacity Reservations were confined to an AWS account. By sharing Capacity Reservations, organizations with EC2 usage spread across multiple AWS accounts can plan for capacity needs at an aggregate level. Workloads with fluctuating or complementary compute needs running in different accounts can tap into centrally reserved EC2 capacity. As a result, organizations can optimize costs by increasing utilization of reserved capacity. This feature is available at no additional cost.