Bullet proof strategy??

Let say SPY is trading at 109.27 now, and here is the price of its option chain.

		Strike Price
5.15	5.29	107	3.45	3.46
4.47	4.61	108	3.81	3.91
3.81	3.95	109	4.2	4.29
3.25	3.3	110	4.58	4.74

Lets assume this.
Long 1 107c, Short 107p = (5.29-3.45) = 1.84, similar to i buy 100 SPY @ (107+1.84).
Short 100 SPY @ 109.27
Profit = 109.27 -108.84 = 0.43

	107c @ 5.29	107p @ 3.45	SPY 109.27
100	-5.29	-3.55	9.27	0.43
105	-5.29	1.45	4.27	0.43
110	-2.29	3.45	-0.73	0.43
115	2.71	3.45	-5.73	0.43

So there are confirm profit 0.43.

But is it worth?
Let's calculate cost. Commision fees excluded.
Cost = Long 107c, Short 107p = 184.00
Short 100 SPY @ 109.27 = -10927.
Profit = 43.
Sound like we are using (10927+184) just to earn 43, which is 0.387% in 30 days, or 4.64% per anuum.

How if commision included?

While open the position,
Long/Short = 10+(0.75*2) = 11.50
Short SPY = 10
Total = 21.50

While close the position, there might be 3 scenario, (i) Stock price < price ="="> strike price.
Let's ignore scenario (ii), it is very unlikely to happen.
Scenario (i) and (iii) will have same cost, which is
one option expired worthless, one being assigned. = 20
Close SPY = 10.
Total cost = 30.

Total cost = 30 + 21.50 = 51.50.
Profit = (43-51.50) = -8.50.

So this does not work for 1 option, but what if 10?
Total cost = (25+10) + (20+10) = 65
Profit = (430-65) = 365

Return for the trade in %.
365/(1840+109270) = 0.32%, or 3.94% per annum.

3.94% per annum?
Sound like is the rate we can get if we put the money in the bank. Then why should we make our so difficult to trade on this, sort of 0% return trade?

As far as I knew, if we short a stock, we no need to pay for full amount. It just need 500 for each 100 stock you short. So actual cost u needed to open the trade is actually, 1840+5000 = 6840.
After Math, it would be 5.33%, or 64% per annum.

Wow, 64%........

Will we got margin call if the stock spike?
Nope. We will got margin call, when the account value is less than the amount we risk.
When the stock spike, although the value of stock is depreciating, but the value of call option is appreciate. It will offset the difference, and make your account value unchanged.

What's next?
With the bid/ask spread closer when the market open, the return would be more attractive.
The next thing I would like to confirm is, whether this strategy can be placed on real trade. I got to wait until Monday to do this. Let's see how.