from my many years in the financial industry I can tell you that in a setup such as this, where GS downgrades a stock that has already been flogged to death and downgraded by others, it has almost been universally a move designed to buy the stock cheap, in this case enabling the shorts to be covered at the lowest possible prices and for those wishing to build a long position to also benefit by buying low.
I am officially retired but still have contacts on institutional trading desks and may check later. Dollars to donuts, GS trading desk will be one of the biggest if not the biggest net buyer of HK stock today. As George Bailey would say, "Potter isn't selling. Potter's buying! And why? Because we're panicking and he's not. !"
It is plain silly to give away HK stock to your enemies.
You would no think they could get away with that because as people leave the
company they would report that is going on. But that being said to wait to down grade a
stock when it is just off its 52 week low does not reflect very good on them. Where was their
down grade when the stock was 2030% higher?