The ornamental design for a merchandisesecuritytag, as shown and described.
FIG. 1 is a perspective view of a merchandise tag showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7. Is a bottom plan view thereof.
The broken lines provided as part of some of the views are included for the purpose of illustrating environmental structure and form no part of the claimed design.