I have the following graph in excel, and I would like to add a single line at the level of the zero on the secondary axis

I thought choosing "horizontal axis cuts on axis=0" in "format axis" options would do it but it seems to have no impact. I'm starting to suspect this is one of the many flaws of post-2007 Excel graphs design. Is there a way I can add this single horizontal line at the zero level with Excel 2013 ?

Edit : For the avoidance of all doubt, this graph is updating, so I would need the line to move along with the zero on the right axis.

I could draw manually a line but it wouldn't feel very satisfying

`Insert > Shapes`

then draw a line on the chart?Is there a way I can add this single horizontal line". You need to add any specific requirements for a solution to your question. Otherwise, we have no idea what you expect. FWIW, I have used this, and the suggestion from Engineer Toast, with great results.