allocationStrategy

Specifies one of the following strategies to launch Spot Instance fleets: price-capacity-optimized, capacity-optimized, lowest-price, or diversified. For more information on the provisioning strategies, see Allocation strategies for Spot Instances in the Amazon EC2 User Guide for Linux Instances.

When you launch a Spot Instance fleet with the old console, it automatically launches with the capacity-optimized strategy. You can't change the allocation strategy from the old console.