You're right, it's not fixed. It caps at 14% for outside brands, 15% for "Kirkland" brands, but averages at 11% (2019). https://www.inc.com/jeff-haden/how-does-costco-compete-with-...

Contrast to markups of 25 to 50% for typical retail, and for generic drugs in the thousands. https://www.thepharmaletter.com/article/1-000-pharmacy-mark-...

That inc article is the only place I see those margin caps and it doesn't come sources. Other articles say that costco doesn't publish their margins.

However, their financial statements do indicate an 11% average gross markup.

But there are definitely plenty of products marked up more than 18% at Costco. Either that or they are paying way too much for some things.

Still waiting for the clarification. You nailed the denunciation, though.