Trading volume in TSLA is low today, which implies that the share price drop is not due to institutional selling. However the low volume does ease the job for manipulators. By pushing down the share price, they would hope to scare weak longs out of their positions and to encourage fresh shorting ahead of Tesla's report of quarterly delivery numbers. As soon as the manipulators have accomplished that mission, they likely will quickly cover their shorts and perhaps go long.
In my opinion, focus on quarterly delivery numbers can be misleading. Sights should be directed longer term regarding the likelihood of the eventual dominance in transportation by autonomous electric vehicles in general and Tesla in particular.
EDIT: As noted by
@madodel, today is Jewish New Year, which would explain the light trading volume, not only in TSLA, but also in the overall market.
Years ago in this video, Jim Cramer explained how manipulation is accomplished: