Coincidentally, that's when BTC started dropping.
People started cashing out to USDT.
USDT value increased.
Uh, oh...USDT needs to be 'stable'...it needs to be 1:1 with actual USD.
Let's print some more USDT to reduce its value.
However, in doing so, Tether is effectively propping up the value of BTC .
Especially as Bitfinex (highest BTC /USD exchange) considers USD and USDT to be interchangeable...
Even though USDT is a non-redeemable token!
For past 5 days they have printed at least 100 million USDT per day...and used it to buy bitcoin...