Double Calendars vs. Double Diagonals
07/29/2013 8:00 am EST
Both of these option strategies have the same fundamental structure; i.e. each is short option contracts in nearby expirations and long option contracts in farther out expirations in equal numbers, writes option trader Dan Passarelli of Market Taker Mentoring.
As implied by the name, this complex spread is comprised of two different spreads. These time spreads (also known as horizontal spreads and calendar spreads) occur at two different strike prices. Each of the two individual spreads, in both the double calendar and the double diagonal, is constructed entirely of puts or calls. But the either position can be constructed of puts, calls, or both puts and calls. The structure for each of both double calendars or double diagonals thus consists of four different, two long and two short, options.
These spreads are commonly traded as “long double calendars” and “long double diagonals” in which the long-term options in the spread (those with greater value) are purchased, and the short-term ones are sold. The profit engine that drives both the long double calendar and the long double diagonal is the differential decay of extrinsic (time) premium between shorter-dated and longer-dated options.
The main difference between double calendars and double diagonals is the placement of the long strikes. In the case of double calendars, the strikes of the short and long contracts are identical. In a double diagonal, the strikes of the long contracts are placed farther out-of-the-money) OTM than the short strikes.
Why should an option trader complicate his or her life with these two similar structures? The reason traders implement double calendars and double diagonals is the position response to changes in IV; in optionspeak, the vega of the position. Both trades are vega positive, theta positive, and delta neutral—presuming the price of the underlying lies between the two middle strike prices—over the range of profitability. However, the double calendar positions, because of placement of the long strikes closer to ATM responds favorably more rapidly to increases in IV while the double diagonal responds more slowly. Conversely, decreases in IV of the long positions impacts negatively double calendars more strongly than it does double diagonals.
By Dan Passarelli, Founder, Market Taker Mentoring