Here are the current most volatile stocks in the S&P 500:

Volatility is defined as the annualized standard deviation of lognormal returns. This is equivalent to realized volatility as defined by option traders. Calculations are all YTD, as of Aug 18th, 2011.

All of the above were calculated using The RiskAPI Add-In.

The events in the equity markets in the last 10 days have been nothing less than extraordinary, to say the least.Here are some stats on the S&P 500 Index prior to July 28th:

• YTD Return: 6.43%
• YTD Realized volatility: 13.05%
• YTD Correlation to gold: 0.05

Here are the same stats with data since 7/28 included.

• YTD Return: -6.49%
• YTD Realized volatility: 19.67%
• YTD Correlation to gold: -0.18

Very significant market impacts have taken place here.

All of the above were calculated using The RiskAPI Add-In.