Deutsche Bank mysteriously referred to “perimeter reductions” in its results last month. The German bank has been peppering its annual results with the term (and the even vaguer “perimeter adjustments”) since at least 2015. But what exactly is a perimeter? And how does one reduce it?

It is not a term other banks or big companies use. Nor could I find any definition of it online, other than the one I learned in GCSE maths. So I asked Deutsche Bank’s press office exactly what it meant. They told me: “We use the word ‘perimeter’ to mean the scope of our business activities, so reducing the business perimeter means scaling back the number of products we offer.”