Ok, this time I want to write in English becuase more easily to express my view:
1/ The straddle I did on 2628 long 33p & 35c was totally wrong. The thing is that the market is very very quiet. You can see from stock graph, the market is just fluctuate beteween 20000. I missed a change to stettle this rubbish trade when 2628 reach 32.x & 36.x
2/ This trade is rubbish because now I am facing "vol crush". The trade I did is Dec options which can relucant to Theo but not Vega !!! IV drops from 40 to now 31, it kills my trade. The thea lose $1 of my combined options value.
3/ I did this trade on late Aug, the front month IV was 36 and the back month was 39, which got decent % difference. It was not a good entry point. A bad volatility skew
4/ This type of calender spread was very popular by advanced options trader. The ppl select their opitons sticke price usually 1std +/- . The trade I did when 2628 was 34.1 so it basically a ATM options.
5/ buy a straddle for 20% IV. if you hedge each day, you need to adjust at standard deviation points in the stock that exceed 20% actual volatility moves. alternatively you can hedge by selling options with >20% IV or purchasing options that are less than 20% IV. So 40% IV of 2628 1 std = +/- $7.x by 120 days from expiration. To sell 40% IV, now is difficult.
6/ Short vol into earnings is that the short gamma can kill you. one method to overcome is to short back back month options (6 months more) .Theoretical you would want Delta/Vega/Theta to be real small Gamma to be big.
7/ Spread loss can cause an instant 10 to 15% loss per leg for a total of an instant 30% loss the very moment you put on a straddle! This is even worse if you put a straddle on options that have very wide bid ask spreads. The combined effect of these losses create a situation where you can profit only when a stock moves EXPLOSIVELY in one direction with a large magnitude...
8/ buy + selling in different months is a very advanced and complex trade which I didn't think about it before. My feeling is that this strategy is the real light to have decent profit, but I am sure at this moment, I am not capble to do these kinds of trade. I am not recommend to any non-expert trader, including me. I will stick on my plan and cut my straddle when reach 50% loss.