Display screen or portion thereof with an animated graphical user interface

[0001]FIG. 1 is a front view of a first image in a sequence for a display screen or portion thereof with an animated graphical user interface showing the new design; and,

[0002]FIG. 2 is a front view of a second image thereof.

[0003]The outermost broken line rectangle illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining long dash-long dash and short dash-short dash broken lines illustrate portions of the graphical user interface that form no part of the claimed design.

[0004]The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-2. The process or period in which one image transitions to another forms no part of the claimed design.