Yes, clearly the 05/02 drop came from a bull market. Yet in % terms, it doesn't even come in the worst 100 days on the Dow since 1900.
Flash crashes are more news worthy and put on the big 4 news programs, they will normally lead out with worst depressing stories, and since most newspapers and TV stations are democrat owned, you hear it the loudest with a Republican President in office.
Be that as it may, whichever way news reports can make it seem worst as in points instead of percentage of drop, that's what they will use. Can you imagine one day it will be Dow 50,000 and it drops 2,000 points and people will be going nuts and that only be 4% move.
When people live, they mostly think in negativity first, they don't wake up to it's a beautiful day, they think what sob at work going to mess with them, majority of people are negative, and seems like this forum, we never discuss those who don't post, they too busy working their trading plans or trade automation and make decisions when they come home, or they work for brokerages, props etc.
Reason of flashes crashes is Hedge funds actually hedging and selling thousands of lots of Index futures and buying thousands of lots of Financials, flight to quality, they are long the stocks, so they don't want to exit and lose dividends and selling billions of dollars of stocks would cause financial collapse , if it is extended decline, they have to sell some stocks as people will be exiting the funds. And to dump a billion plus dollars of stocks is no easy feat by one firm and how many Hedge funds in the world? But they have to do what they have to do and sell to generate cash to send back to those requesting them. As far as why no flash rallies, where is Hedge funds going to get the new money in a heartbeat? They only have so much money to buy stocks and they require enough so investors can ask for proceeds to liquidate cause Johnny needs new shoes. Indexes do go up pretty nicely when Hedge funds get out of the hedges by buying and some will buy even more to get some of the extension of recovery to making new highs or very least decent percentage of the drop.
So I believe it is supply and demand of cash on hand.