People could place orders before trading started. I was watching BCH/USD and BCH/BTC which had a fixed price, $3100 USD and 3.00 BTC respectively.
BCH/USD had a huge amount of buy pressure (people buying BCH with cash); BCH/BTC had a huge amount of sell pressure (people dumping the airdrop).
Only BCH/USD went live; BCH/BTC remained paused. (That was weird, I thought it looked like a human somewhere hit enter too soon, but apparently it was intended)
Once trading started (BCH/USD only), people couldn't place new sell orders. The unlimited buys cleared, including the guy on reddit whose order was "Buy $100000 USD of BTC at market price", which was filled at 6k and then he was unable to place a sell at 9k. Apparently placing buys without limits is common because unlimited buys are filled before limited ones are.
Since you couldn't place a new sell; the price was not bounded; the book cleared and everything was stuck at 9.5k for a couple minutes. There was a little bit of trades, not sure if it was only people with existing orders that were glitched or if maybe some people weren't glitched, maybe all the activity was orders placed before trading opened.
They realized the issue and paused trading; orders began to accumulate again roughly around here; here's a screenshot of the orders accumulating https://i.imgur.com/0NTyYXx.png There is incredible sell pressure here, the price was obviously out of whack with actual supply/demand.
(MY SPECULATION) Since there was never a functioning market I'd expect Coinbase to rewind all the trades which is what it looks like they are doing.
I might have gotten some of the details wrong, I am just a detached layperson learning about finance who happened to see this go down.
Sorry reddit, no consipiracy here. But none of those posts in r/bitcoin are actual humans anyway, it's all fake bots and a couple poor suckers who don't realize they're arguing with a content farm. Here's some required reading about the bitcoin information manipulation shitshow. https://np.reddit.com/r/BitcoinMarkets/comments/6rxw7k/infor... TLDR: Nothing is real, everything is fake news, you think it can't possibly be that bad? it's actually worse than that.