Those investment banks are only nominee accounts, ie are not the...

Those investment banks are only nominee accounts, ie are not the actual shareholders. They are likely a collection of dozens of institutional investors who use nominee accounts for legal or anonymity reasons. Paper below is a good albeit old discussion.

It is a legal requirement that holders above 5% must declare their position and there are only Ruffer and Van Eck in that category.

Those institutional investors can have various motives for holding too. I’d say they are no more likely to be long term holders than the people who post on HotCopper.

https://digital.library.adelaide.edu.au/dspace/bitstream/2440/24879/1/alr_V5n2_1975_BluNom.pdf