Largest 10 Year Treasury Futures Block Trade EVER? Whats happening in the rates market? [9LIV9G6Jl7Q]

Bloomberg reported yesterday that someone sold 78,000 10-year Treasury contracts in the London session on Tuesday, making it the largest block futures trade in TYs in over 12 years, possibly EVER. We break down the price action, possible theories behind the investor's motivation, and explain the immediate aftermath that has the seller marking up anywhere from $25-50mm in just over 24 hours!!