Display screen or portion thereof with an animated graphical user interface

FIG. 1 is a front view of a first image in a sequence for a first embodiment of a display screen or portion thereof with an animated graphical user interface showing the new design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a first image in a sequence for a second embodiment of a display screen or portion thereof with an animated graphical user interface showing the new design; and,

FIG. 4 is a front view of a second image thereof.

The outermost broken line rectangle illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface that form no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 - 2 and FIGS. 3 - 4 . The process or period in which one image transitions to another forms no part of the claimed design.