Ah, yes, didn't think about this...
A straddle offsets both delta and gamma.
A synthetic straddle offsets delta, but not gamma.
A synthetic position is therefore more responsive to moves in the underlying.
Thanks.
No, it's exactly the same... a delta-hedged call has the same delta, same gamma, same vega as a straddle....
Although, you need to trade 2 SPX calls with 1 SPX future... or 2 SPX calls with 2 ES futures to get a full straddle. Otherwise it's half a straddle.
1 ATM call has the same gamma as 1 ATM put, so 2 ATM calls have the same as 1 straddle or 2 puts...