At 1532ET today (Columbus Day - with half the market absent), someone - apparently having waited to see if the almost 'ubiquitous' 330pm Ramp would occur - decided it was time to dump three-quarters of a billion dollars notional of US equity market exposure in 1 second. The results of this forced liquidation (or utter disregard for fiduciary duty) were as follows...

A complete collapse of all liquidity in the S&P 500 e-mini futures contract - the world's most liquid equity exposure vehicle...

The liquidity evaporation began at 15:32:37 after 4,492 eMini contracts were dumped in 28 milliseconds $ES_F $SPY — Eric Scott Hunsader (@nanexllc) October 13, 2014

An instantaneous 9 point plunge in the S&P 500...

And total chaos in the S&P 500 ETF (SPY) which saw offers below bids for what is hours to liquidity-providing HFTs (who appeared to step away for coffee)...

This chart shows just 1 second of SPY trading (corresponding to the volume spike above)

As Nasdaq quotes fell dramatically behind reality...

Given that NYSE margin debt at record highs and investor net worth at record lows...

The vicious cycle feedback from any extended push lower on liquidations is more than a little concerning (and may well explain the aggressive VIX buying today - and massive inversion of the VIX term structure)

Charts: Bloomberg and Nanex and @noalpha_allbeta

