For anyone who hasn't been following, the prevailing theory is that the largest Cryptocoin exchange "Bitfinex" also runs an altcoin called "Teather" which was marketed as being backed 1:1 by USD. So far they've created 2.8 BILLION USDT and coincidently the times they create millions of these happens to be in the middle of extreme market crashes.
See this chart: https://i.imgur.com/Uo07d1d.jpg
More details here:
https://medium.com/cryptomedication/uncovering-the-real-cart...
https://medium.com/@bitfinexed/latest
https://medium.com/@mattcollburner/bitmex-insiders-caught-in...