I thought it would be the Sigma and I found some data on it at DPreview
Here is a relevant part of the review on dpreview focal length V aperture data (scroll to bottom of page):
https://www.dpreview.com/reviews/sig...5-6p3-os-n15/2
As discussed earlier - It is f6.3 at 200mm. If you were thinking that using the blutak to hold the lens iris open will allow you to achieve a larger aperture, it won't. For that sort of lens (high ratio wide/tele zoom)it will be f6.3 at maximum opening, governed by design constraints (physical lens and iris sizes) inside the lens.
If you want a fast 200mm lens for Canon, there are some Full-frame f/2 and f/2.8 alternatives from others as well as Canon, although the Canon lenses are many times more expensive.
Best
JA