Shares of Datadog (DDOG -4.23%) shot up nearly 15% on July 3 after it was revealed that the provider of cloud-based observability, monitoring, and security solutions will join the S&P 500 index on July 9. Datadog will be replacing Juniper Networks in the index after the latter was acquired by Hewlett Packard Enterprise. It is easy to see why Datadog's inclusion in the index has sent its stock soaring. To enter the index, a company needs to demonstrate solid profitability in the past four quarters, along wit ...