In this post, we are going to examine a trading system with the goal of using it as a hedge for long equity exposure. To this end, we test a simple, shortonly momentum system. The rules are as follows, Short at the close when Close of today < lowest Close of the last 10 days Cover at the close when Close of today > lowest Close of the last 10 days The Table below presents results for SPY from 1993 to the present. We performed the tests for 2 different volatility regimes: low (VIX<=20) and high (VIX>20). Note that we have tested other lookback periods and VIX filters, but obtained qualitatively the same results.
It can be seen that the average PnL for all trades is 0.3%, so overall shorting SPY is a losing trade. This is not surprising, since in the short term the SP500 exhibits a strong mean reverting behavior, and in a long term it has a positive drift. We still expected that when volatility is high, the SP500 would exhibit some momentum characteristics and short selling would be profitable. The result indicates the opposite. When VIX>20, the average trade PnL is 0.37%, which is higher (in absolute value) than the average trade PnL for the lower volatility regime and all trades combined (0.23% and 0.3% respectively). This result implies that the mean reversion of the SP500 is even stronger when the VIX is high. The average trade PnL, however, does not tell the whole story. We next look at the maximum favorable excursion (MFE). Table below summarizes the results
Despite the fact that the short SPY trade has a negative expectancy, both the average and median MFEs are positive. This means that the short SPY trades often have large unrealized gains before they are exited at the close. Also, as volatility increases, the average, median and largest MFEs all increase. This is consistent with the fact that higher volatility means higher risks. The above result implies that during a selloff, a long equity portfolio can suffer a huge drawdown before the market stabilizes and reverts. Therefore, it’s prudent to hedge long equity exposure, especially when volatility is high. An interesting, related question arises: should we use options or futures to hedge, which one is cheaper? Based on the average trade PnL of 0.37% and gamma rent derived from the lower bound of the VIX, a back of the envelope calculation indicated that hedging using futures appears to be cheaper. See More Here: A Simple System For Hedging Long Portfolios
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We have written many blog posts about the increase in volatility of volatility. See, for example Is Volatility of Volatility Increasing? What Caused the Increase in Volatility of Volatility? Similarly, last week Bloomberg reported, The sudden rise in volatility in February and March showed that even with strong growth fundamentals, financial markets remain vulnerable. Since 2008, there have been seven flash crashes followed by sudden recoveries. Volatility has become binary, with markets swinging between periods of shock and calm. The VIX index traded at a median of 16 after the start of QE and at 18 before, but the spikes in volatility have become twice as frequent. It is the equivalent of swapping a stable drizzle rain with many days of scorching sun, at the price of occasional natural disasters. Read more [caption id="attachment_454" align="aligncenter" width="628"] VVIX (volatility of volatility index) as at March 23 2018. Source: stockcharts.com[/caption] The rise of the volatility of volatility increases the chance of a Black Swan event happening. Recently, we presented a study showing that a down day of 4% during a bull market is a very rare event. It happened on February 5, and before that the last time this occurred, it was 18 years ago. We next counted the number of days when the SP500 dropped 4% or more during a bull market. We defined the bull market as price > 200Day simple moving average. Since 1970 there have been 5 occurrences, i.e. on average once every 10 years. We don’t know whether this qualifies as a black swan event, but a drop of more than 4% during a bull market is indeed very rare. Read more Similarly, AQR looked at the February 5 event from the implied/realized volatility perspective. ... As of now (no predictions going forward!) this recent wild period is not super crazy when we look just at volatility itself (it’s high, but not super high vs. history). But, when we look at it as a surprise (by comparing the realized 5day volatility to the starting VIX) it’s a considerably more shocking event, though still not unprecedented. Similar events have occurred five or so times in the 1990  present history (again, see the above figure). Finally, when just using the simple method of targeting constant volatility that we employ here, this recent surprise swoon was, as we’d expect, pretty bad for volatility targeters. But, over the longer term, volatility targeting, even the super simple volatility targeting our toy riskmodel employs, may, on average, deliver more downside stability than not volatility targeting and implicitly letting the market dictate the volatility of your investment. Read more Again, from the implied/realized volatility point of view, the recent event was a rare occurrence, though not unprecedented. In times like this, risk management is more important than ever. Post Source Here: Black Swan and Volatility of Volatility 
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