Note that volume of 6-7m shares is pretty low - which suggests the big buyers are inactive, which could be because:
At the same time there's plenty of justification to sell shares - which creates downwards movement.
- one possible reason could be that major shareholders are unable to initiate more buying, because their main Tesla decision makers are in possession of non-public material information, such as the details of the going-private negotiations,
- or Tesla/Elon could have insisted on a freeze on share count for a shareholder to be part of the negotiation process, (to prevent a rush for shares),
- or there's indeed too much uncertainty about the deal to justify more buying.
Also, maybe they don't want to raise the stock price too much, which would necessitate raising the buy-out offer higher than 420?