Given the above information, one may conclude that we are currently on the verge of the stock market equivalent of "sudden cardiac death", but that's not entirely accurate. Although the dominance of HFT in the market has helped destroy healthy variability, it is not the root cause of systemic instability. That designation is more appropriately reserved for the decades-long credit (complexity) bubble which has ensued all around the world, but especially in the United States.My 401K can attest to the accuracy of this analogy.
The reality is that the "critical point" for U.S. financial markets was already reached in 2008, and as most Americans are aware, the markets almost died back then. Cue the federal government and federal reserve, which provided trillions in "liquidity" to artificially create the variability that had been lost. The politicians and central bankers would like to think of themselves as the defibrilator that has sparked the financial "heart" back into a healthy rhythm.
However, that analogy is simply not accurate, as evidenced by the current equity market's painfully boring microstructure. They are more like the artificial respirator that is keeping the brain-dead markets "technically" alive. Their tireless efforts are simply masking the terminal reality that lies underneath, and now we're all just waiting for someone or something to finally pull the plug.