Symbol Marker in Chart

Since you did not include the text box/drawing object you are using to create these custom markers, it is difficult to see exactly what you have done and make suggestions for changes.

I would guess that, when you created the drawing object, you left the object's background property as "solid fill" and the color is probably white. When this object is used in the chart, it will naturally cover up anything "beneath" it on the chart, because it is the < character on top of a white background. If this is the case, then the solution may be to format the object so it has no fill or a transparent background. Then it won't cover the other chart elements when it is used as the series markers

A second possible approach is to use custom data labels instead of series markers. Enter a series of < characters in an adjacent column, use Rob Bovey's XY chart labeler add-in (appspro.com ) to add this column to the desired series as a data label, format so they are positioned in the center, and get rid of the squares.