Log In banners are often necessary according to internal policies for users logging into internal or mission critical applications and tools.
Can a custom banner be added to the Performance Management Log In page?
All supported Performance Management releases
No code exists to support, and no method is known to exist, that provides the ability to add a banner to the Performance Management Log In page(s).
Closest ability is adding a custom logo to the pages post log in as documented here:
The ability to add a banner as described would be a new feature. This can be requested by posting an Idea request to the Performance Management Community site for consideration.