straddle

All of these combinations are bets that implied volatility will increase. A STRADDLE is long a call plus long a put, both at the same strike price (in my example, K = $20). A STRANGLE is also long call plus long put, but the options are out of the money; the strangle is less expensive but...

Hi David. Just wondering: why would an investor choose a butterfly spread over a straddle write if the expectation is that the stock price movement would be minimal? Purely risk considerations? And why would the reverse happen, i.e. an investor chooses a straddle write over a butterfly spread?