Last Hour Market Dumps Due To $32 Billion In Quarter-End Pension Selling

In a painful reminder of what the "market" used to be like a year ago when it didn't magically levitate every single day, there was a powerful market puke today starting at exactly 3:30pm ET some 30 minutes before the close, a time traditionally reserved for the late day ETF/buyback ramp yet which - for the second day in a row - coincided with a surge in spoo volumes and a huge Market on Close for sale imbalance to the tune of $8.1 billion across the last two sessions ($5.3BN today, $2.8BN on Monday).

What was behind the dump?