Also "Mittelstand" is already the German word for the whole group of such companies. It thus hardly makes sense to pluralize this word. If you are talking about an individual company of this group, the correct term is "mittelständisches Unternehmen".

Because of the pluralization? Mittelstands instead of Mittelstand? Now that I see it, I can't unsee it! How ugly! (what a German saying by itself -> "wie hässlich") :D

Because calling it what it is - loan for equity for SMB businesses - isn't as sexy . Using some exotic name for an old thing makes the old boring thing seem better, even when it isn't.