Here’s my guess of the ‘why’ Shenzhen Stock Exchange plunge. A heavily leveraged stock market boom starts to bust requiring margin calls. The ‘were’ to bolster more investment to stop the collapse a Shenzhen-Hong Kong link approved. China’s hihg-tech sector is treading water and about t bust.
We now need the ‘who’ and the ‘what’. I suspect the 'what' is a challenge to the US Saudi petro-dollar alliance. Our Oil-backed monetary system (sorry fiat money geeks, US dollar is backed by oil, and the 51 State is SA).
Anyway still working out the theory.