First of all, I am not a Guru on options, some of the terminology I use will probably be incorrect. From what I understand the reason the tech sector took a plunge was Softbank was buying billions of call options. Options of nearly $4 bn in tech stocks including Amazon, Microsoft, Tesla and Google’s parent Alphabet. I guess the entities that were going to fill the calls, the (puts). Sold off their holding because the stocks were not going up like the calls were suppose to. Market plunged, maybe other factors. I believe Softbank did not buy call options on Apple, Apple just got caught in the middle of it all.
With that all said, a investor could sort thru the calls and puts and figure out maybe if this same type of scenario would unfold again, but. Damm that would be very time consuming. Has anyone ever or does anyone use Ninja Trader or Market Delta? I read these two systems can and could identify these types of trends. Does anyone know? Which system is better? I heard Ninja Trader. Any advice would be helpful.

They are both good, but any platform will have charting and analysis tools. To identify trends and reversals etc, you will need to learn a little about technical analysis. Regarding SFTBF they made a big directional bet pushing value up in a market where valuations were high already and sustainable, acting like a hedge fund, which they are not.