I am afraid this is the shot across the bow. ETFs are destroying the markets in my opinion. One only has to observe the action last Monday on the Dow’s 1000 point plunge at the open to understand the instability they wrought.
Huge temporary declines in some exchange-traded funds, including Vanguard Dividend Appreciation (VIG) and SDPR S&P Dividend (SDY), show pitfalls during stretches of stock-market stress
Source: Market Plunge Provides Harsh Lessons for ETF Investors