How do you shade below a specific gridline of a line graph?

Hi all,

I'm trying to set up a line graph based on a cash forecast for one of my clients.

Because of the nature of the business the directors have assessed that there needs to be a minimum level of cash in the bank each morning.

Going forward there are at least 4 occasions and possibly more where the line graph drops below this figure.


As the cash flow can fluctuate by millions on occasion the graph line can drop below the minimum figure by one or several grid lines.


What I want to do is to have the area of the graph below the grid line that corresponds to this minimum figure shaded (preferably in red). The intention is to make it immediately clear where the line graph drops below that minimum figure and into the red.


I'm not sure how to do this or if it's even possible. Anyones help would be appreciated.

Thanks Andy.

I understand the concept of your reply but don't think the mechanics are clear to me - probably indicative of my average charting skills.


Going through it I've used a shadow effect through the secondary axis which sort of does the job.

However, I'd love to know the actual steps you're recommending in your reply as the example you have is far more effective.