Display Screen or Portion Thereof with an Animated Graphical User Interface

FIG. 1 is a view of a first transitional image of a display screen with an animated graphical user interface; and, FIG. 2 is a view of a second transitional image of a portion of a display screen with an animated graphical user interface. The appearance of the transitional image sequentially transitions between the images shown in FIG. 1 - 2 . The process or period in which one image transitions to another image forms no part of the claimed design. The claimed subject matter in FIG. 2 aligns with the same subject matter in FIG. 1 . The long-short-long-dashed broken line is included for the purpose of illustrating a display screen or portion thereof and forms no part of the claimed design. The evenly-dashed broken line is included for the purpose of illustrating an animated graphical user interface and forms no part of the claimed design.