Quote from rdemyan:
Rich:
I only trade bear calls now. I put on some AUGUST positions last week that after the big drop this week I was able to sell and retain over 75% of the credit.
So still have about 5 weeks until August expiration and I'm looking to go again with some August bear call positions.
If I use the following formula to calculate a standard dev:
stock price * volatility * square root of days to exp/365
I get:
1236 * .1549 * sqrt(33/365) = 57.43
where volatility is taken at an option strike of 1235.
Multiplying by 2 for two SDs yields 114.9
115 plus 1236 is 1351 so a short strike at 1350 meets the two SDs.
Did I err in my calculation?
rydeman, I think given the current market and Heather's previous comment "the bear goes out the window" trading only bearish call spreads makes sense. I figure I have just over another week to consider putting any put positions so I'm in no rush.
Regarding your formula if it is correct or not, I am not sure perhaps others here can comment.
What I do is calculate the formula based upon SPX closing data over the last 12 months. I have Excel calculating one standard deviation, then I also calculate 1.5 and 2.
Good luck in your trading!