NewsWatch: What’s really to blame for the sudden shattering of the stock market’s calm?

Irrational exuberance has been momentarily exorcised from Wall Street. A raucous week ended with the stock market posting the most brutal declines in about two years What went wrong after a lengthy period of such calm?
Source: Marketwatch Bitcoin News
Link: NewsWatch: What’s really to blame for the sudden shattering of the stock market’s calm?