Should I be worried about my DIY-Excel behaviour?

Kees de Koning
Publish date

You love Excel. You can do everything with it. It's back testing a new asset mix, a prototype report automation or a new idea about real time calculations of fair values. But you feel apprehensive as well because you know that these Excel sheets have the potential to become the next production critical application.

Your awesome IT department is too backlogged with work regarding the latest MiFID II obligations to discuss the practical problem you need to deal with… should you wait?

You can't. You love Excel. It's just so easy to extract and link data files from third party systems (Bloomberg, Simcorp, ...) to your Excel sheet, add some beautiful VBA code, apply some conditional formatting and your imagination is unstoppable. Before you know it you have your first homemade prototype Excel reporting tool. Ha! Beat that, in just a few days!

Should this EXCELent behaviour be discouraged? No. I think you should be cheered and commended for your initiative and accomplishment.

Prototyping is an ideal way to test that something works. Make your first prototype in Excel. It helps you get acknowledgement for your problem and create support for it. You are by far the best person to create this first (Excel-)prototype. You know what you want to achieve, you understand the data, the priorities and the possible pitfalls.

Now! The moment for intervention! I advise you to take a step back once you discover the first signs that your Excel sheet is being used for production (critical) processes. (First signs are: You’re being called while on the beach to fix yet another #REF! problem.) From there, create a small project from it. Describe using a brief business case what the problem is, how it is currently resolved (your Excel sheet) and figure out what is needed to make that first step towards creating a more sustainable solution. Note that it is often easier for a third person to write this, rather than you doing it yourself.


  • Keep building Excel sheets, which have the potential to be production critical applications;
  • Build internal support and make a project plan before the Excel sheet becomes that production critical application;
  • Have the first version (MVP) or second prototype, built in-house or at a specialized agency;
  • Be the product owner of that team. Have full control of your project and the product.

And a final note: Arrange SLA’s with the development team / the department / the company so you won’t be the one being called while on vacation to solve errors anymore.

Happy Excelling :)

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