CHAPTER 11
Calendar and Diagonal Spreads
Option selling is a niche that attracts many retail and professional traders because it’s possible to profit from the passage of time. Calendar and diagonal spreads are practical strategies to limit risk while profiting from time. But these spreads are unique in many ways. In order to be successful with them, it is important to understand their subtle qualities.
Calendar Spreads
Definition
: A calendar spread, sometimes called a
time spread
or a
horizontal spread
, is an option strategy that involves buying one option and selling another option with the same strike price but with a different expiration date.
At-expiration diagrams do a calendar-spread trader little good. Why? At the expiration of the short-dated option, the trader is left with another option that may have time value. To estimate what the position will be worth when the short-term option expires, the value of the long-term option must be analyzed using the greeks. This is true of the variants of the calendar—double calendars, diagonals, and double diagonals—as well. This chapter will show how to analyze strategies that involve options with different expirations and discuss how and when to use them.
Buying the Calendar
The calendar spread and all its variations are commonly associated with income-generating spreads. Using calendar spreads as income generators is popular among retail and professional traders alike. The process involves buying a longer-term at-the-money option and selling a shorter-term at-the-money (ATM) option. The options must be either both calls or both puts. Because this transaction results in a net debit—the longer-term option being purchased has a higher premium than the shorter-term option being sold—this is referred to as buying the calendar.
The main intent of buying a calendar spread for income is to profit from the positive net theta of the position. Because the shorter-term ATM option decays at a faster rate than the longer-term ATM option, the net theta is positive. As for most income spreads, the ideal outcome occurs when the underlying is at the short strike (in this case, shared strike) when the shorter-term option expires. At this strike price, the long option has its highest value, while the short option expires without the trader’s getting assigned. As long as the underlying remains close to the strike price, the value of the spread rises as time passes, because the short option decreases in value faster than the long option.
For example, a trader, Richard, watches Bed Bath & Beyond Inc. (BBBY) on a regular basis. Richard believes that Bed Bath & Beyond will trade in a range around $57.50 a share (where it is trading now) over the next month. Richard buys the January–February 57.50 call calendar for 0.80. Assuming January has 25 days until expiration and February has 53 days, Richard will execute the following trade:
Richard’s best-case scenario occurs when the January calls expire at expiration and the February calls retain much of their value.
If Richard created an at-expiration P&(L) diagram for his position, he’d have trouble because of the staggered expiration months. A general representation would look something like
Exhibit 11.1
.
EXHIBIT 11.1
Bed Bath & Beyond January–February 57.50 calendar.
The only point on the diagram that is drawn with definitive accuracy is the maximum loss to the downside at expiration of the January call. The maximum loss if Bed Bath & Beyond falls low enough is 0.80—the debit paid for the spread. If Bed Bath & Beyond is below $57.50 at January expiration, the January 57.50 call expires worthless, and the February 57.50 call may or may not have residual value. If Bed Bath & Beyond declines enough, the February 57.50 call can lose all of its value, even with residual time until expiration. If the stock falls enough, the entire 0.80 debit would be a loss.
If Bed Bath & Beyond is above $57.50 at January expiration, the January 57.50 call will be trading at parity. It will be a negative-100-delta option, imitating short stock. If Bed Bath & Beyond is trading high enough, the February 57.50 call will become a positive-100-delta option trading at parity plus the interest calculated on the strike. The February deep-in-the-money option would imitate long stock. At a 2 percent interest rate, interest on the 57.50 strike is about 0.17. Therefore, Richard would essentially have a short stock position from $57.50 from the January 57.50 call and would be essentially long stock from $57.50 plus 0.28 from the February call. The maximum loss to the upside is about 0.63 (0.80 − 0.17).
The maximum loss if Bed Bath & Beyond is trading over $57.50 at expiration is only an estimate that assumes there is no time value and that interest and dividends remain constant. Ultimately, the maximum loss will be 0.80, the premium paid, if there is no time value or carry considerations.
The maximum profit is gained if Bed Bath & Beyond is at $57.50 at expiration. At this price, the February 57.50 call is worth the most it can be worth without having the January 57.50 call assigned and creating negative deltas to the upside. But how much precisely is the maximum profit? Richard would have to know what the February 57.50 call would be worth with Bed Bath & Beyond stock trading at $57.50 at February expiration before he can know the maximum profit potential. Although Richard can’t know for sure at what price the calls will be trading, he can use a pricing model to estimate the call’s value.
Exhibit 11.2
shows analytics at January expiration.
EXHIBIT 11.2
Bed Bath & Beyond January–February 57.50 call calendar greeks at January expiration.
With an unchanged implied volatility of 23 percent, an interest rate of two percent, and no dividend payable before February expiration, the February 57.50 calls would be valued at 1.53 at January expiration. In this best-case scenario, therefore, the spread would go from 0.80, where Richard purchased it, to 1.53, for a gain of 91 percent. At January expiration, with Bed Bath & Beyond at $57.50, the January call would expire; thus, the spread is composed of just the February 57.50 call.
Let’s now go back in time and see how Richard figured this trade.
Exhibit 11.3
shows the position when the trade is established.
EXHIBIT 11.3
Bed Bath & Beyond January–February 57.50 call calendar.
A small and steady rise in the stock price with enough time to collect theta is the recipe for success in this trade. As time passes, delta will flatten out if Bed Bath & Beyond is still right at-the-money. The delta of the January call that Richard is short will move closer to exactly −0.50. The February call delta moves toward exactly +0.50.
Gamma and theta will both rise if Bed Bath & Beyond stays around the strike. As expiration approaches, there is greater risk if there is movement and greater reward if there is not.
Vega is positive because the long-term option with the higher vega is the long leg of the spread. When trading calendars for income, implied volatility (IV) must be considered as a possible threat. Because it is Richard’s objective to profit from Bed Bath & Beyond being at $57.50 at expiration, he will try to avoid vega risk by checking that the implied volatility of the February call is in the lower third of the 12-month range. He will also determine if there are any impending events that could cause IV to change. The less likely IV is to drop, the better.
If there is an increase in IV, that may benefit the profitability of the trade. But a rise in IV is not really a desired outcome for two reasons. First, a rise in IV is often more pronounced in the front month than in the months farther out. If this happens, Richard can lose more on the short call than he makes on the long call. Second, a rise in IV can indicate anxiety and therefore a greater possibility for movement in the underlying stock. Richard doesn’t want IV to rock the boat. “Buy low, stay low” is his credo.
Rho is positive also. A rise in interest rates benefits the position because the long-term call is helped by the rise more than the short call is hurt. With only a one-month difference between the two options, rho is very small. Overall, rho is inconsequential to this trade.
There is something curious to note about this trade: the gamma and the vega. Calendar spreads are the one type of trade where gamma can be negative while vega is positive, and vice versa. While it appears—at least on the surface—that Richard wants higher IV, he certainly wants low realized volatility.
Bed Bath & Beyond January–February 57.50 Put Calendar
Richard’s position would be similar if he traded the January–February 57.50 put calendar rather than the call calendar.
Exhibit 11.4
shows the put calendar.
EXHIBIT 11.4
Bed Bath & Beyond January–February 57.50 put calendar.
The premium paid for the put spread is 0.75. A huge move in either direction means a loss. It is about the same gamma/theta trade as the 57.50 call calendar. At expiration, with Bed Bath & Beyond at $57.50 and IV unchanged, the value of the February put would be 1.45—a 93 percent gain. The position is almost exactly the same as the call calendar. The biggest difference is that the rho is negative, but that is immaterial to the trade. As with the call spread, being short the front-month option means negative gamma and positive theta; being long the back month means positive vega.
Managing an Income-Generating Calendar
Let’s say that instead of trading a one-lot calendar, Richard trades it 20 times. His trade in this case is
His total cash outlay is $1,600 ($80 times 20). The greeks for this trade, listed in
Exhibit 11.5
, are also 20 times the size of those in
Exhibit 11.3
.
EXHIBIT 11.5
20-Lot Bed Bath & Beyond January–February 57.50 call calendar.
Note that Richard has a +0.18 delta. This means he’s long the equivalent of about 18 shares of stock—still pretty flat. A gamma of −0.72 means that if Bed Bath & Beyond moves $1 higher, his delta will be starting to get short; and if it moves $1 lower he will be longer, long 90 deltas.
Richard can use the greeks to get a feel for how much the stock can move before negative gamma causes a loss. If Bed Bath & Beyond starts trending in either direction, Richard may need to react. His plan is to cover his deltas to continue the position.
Say that after one week Bed Bath & Beyond has dropped $1 to $56.50. Richard will have collected seven days of theta, which will have increased slightly from $18 per day to $20 per day. His average theta during that time is about $19, so Richard’s profit attributed to theta is about $133.
With a big-enough move in either direction, Richard’s delta will start working against him. Since he started with a delta of +0.18 on this 20-lot spread and a gamma of −0.72, one might think that his delta would increase to 0.90 with Bed Bath & Beyond a dollar lower (18 − [−0.072 × 1.00]). But because a week has passed, his delta would actually get somewhat more positive. The shorter-term call’s delta will get smaller (closer to zero) at a faster rate compared to the longer-term call because it has less time to expiration. Thus, the positive delta of the long-term option begins to outweigh the negative delta of the short-term option as time passes.
In this scenario, Richard would have almost broken even because what would be lost on stock price movement, is made up for by theta gains. Richard can sell about 100 shares of Bed Bath & Beyond to eliminate his immediate directional risk and stem further delta losses. The good news is that if Bed Bath & Beyond declines more after this hedge, the profit from the short stock offsets losses from the long delta. The bad news is that if BBBY rebounds, losses from the short stock offset gains from the long delta.
After Richard’s hedge trade is executed, his delta would be zero. His other greeks remain unchanged. The idea is that if Bed Bath & Beyond stays at its new price level of $56.50, he reaps the benefits of theta increasing with time from $18 per day. Richard is accepting the new price level and any profits or losses that have occurred so far. He simply adjusts his directional exposure to a zero delta.
Rolling and Earning a “Free” Call
Many traders who trade income-generating strategies are conservative. They are happy to sell low IV for the benefits afforded by low realized volatility. This is the problem-avoidance philosophy of trading. Due to risk aversion, it’s common to trade calendar spreads by buying the two-month option and selling the one-month option. This can allow traders to avoid buying the calendar in earnings months, and it also means a shorter time horizon, signifying less time for something unwanted to happen.
But there’s another school of thought among time-spread traders. There are some traders who prefer to buy a longer-term option—six months to a year—while selling a one-month option. Why? Because month after month, the trader can roll the short option to the next month. This is a simple tactic that is used by market makers and other professional traders as well as savvy retail traders. Here’s how it works.
XYZ stock is trading at $60 per share. A trader has a neutral outlook over the next six months and decides to buy a calendar. Assuming that July has 29 days until expiration and December has 180, the trader will take the following position:
The initial debit here is 2.55. The goal is basically the same as for any time spread: collect theta without negative gamma spoiling the party. There is another goal in these trades as well: to roll the spread.
At the end of month one, if the best-case scenario occurs and XYZ is sitting at $60 at July expiration, the July 60 call expires. The December 60 call will then be worth 3.60, assuming all else is held constant. The positive theta of the short July call gives full benefits as the option goes from 1.45 to zero. The lower negative theta of the December call doesn’t bite into profits quite as much as the theta of a short-term call would.
The profit after month one is 1.05. Profit is derived from the December call, worth 3.60 at July expiry, minus the 2.55 initial spread debit. This works out to about a 41 percent return. The profit is hardly as good as it would have been if a short-term, less expensive August 60 call were the long leg of this spread.
Rolling the Spread
The July–December spread is different from short-term spreads, however. When the Julys expire, the August options will have 29 days until expiration. If volatility is still the same, XYZ is still at $60, and the trader’s forecast is still neutral, the 29-day August 60 calls can be sold for 1.45. The trader can either wait until the Monday after July expiration and then sell the August 60s, or when the Julys are offered at 0.05 or 0.10, he can buy the Julys and sell the Augusts as a spread. In either case, it is called rolling the spread. When the August expires, he can sell the Septembers, and so on.
The goal is to get a credit month after month. At some point, the aggregate credit from the call sales each month is greater than the price initially paid for the long leg of the spread, thus eliminating the original net debit.
Exhibit 11.6
shows how the monthly credits from selling the one-month calls aggregate over time.
EXHIBIT 11.6
A “free” call.
After July has expired, 1.45 of premium is earned. After August expiration, the aggregate increases to 2.90. When the September calls, which have 36 days until expiration, are sold, another 1.60 is added to the total premium collected. Over three months—assuming the stock price, volatility, and the other inputs don’t change—this trader collects a total of 4.50. That’s 0.50 more than the price originally paid for the December 60 call leg of the spread.
At this point, he effectively owns the December call for free. Of course, this call isn’t really free; it’s earned. It’s paid for with risk and maybe a few sleepless nights. At this point, even if the stock and, consequently, the December call go to zero, the position is still a profitable trade because of the continued month-to-month rolling. This is now a no-lose situation.
When the long call of the spread has been paid for by rolling, there are three choices moving forward: sell it, hold it, or continue writing calls against it. If the trader’s opinion calls for the stock to decline, it’s logical to sell the December call and take the residual value as profit. In this case, over three months the trade will have produced 4.50 in premium from the sale of three consecutive one-month calls, which is more than the initial purchase price of the December call. At September expiration, the premium that will be received for selling the December call is all profit, plus 0.50, which is the aggregate premium minus the initial cost of the December call.
If the outlook is for the underlying to rise, it makes sense to hold the call. Any appreciation in the value of the call resulting from delta gains as the underlying moves higher is good—$0.50 plus whatever the call can be sold for.
If the forecast is for XYZ to remain neutral, it’s logical to continue selling the one-month call. Because the December call has been financed by the aggregate short call premiums already, additional premiums earned by writing calls are profit with “free” protection. As long as the short is closed at its expiration, the risk of loss is eliminated.
This is the general nature of rolling calls in a calendar spread. It’s a beautiful plan when it works! The problem is that it is incredibly unlikely that the stock will stay right at $60 per share for five months. It’s almost inevitable that it will move at some point. It’s like a game of Russian roulette. At some point it’s going to be a losing proposition—you just don’t know when. The benefit of rolling is that if the trade works out for a few months in a row, the long call is paid for and the risk of loss is covered by aggregate profits.
If we step outside this best-case theoretical world and consider what is really happening on a day-to-day basis, we can gain insight on how to manage this type of trade when things go wrong. Effectively, a long calendar is a typical gamma/theta trade. Negative gamma hurts. Positive theta helps.
If we knew which way the stock was going, we would simply buy or sell stock to adjust to get long or short deltas. But, unfortunately, we don’t. Our only tool is to hedge by buying or selling stock as mentioned above to flatten out when gamma causes the position delta to get more positive or negative.
1
The bottom line is that if the effect of gamma creates unwanted long deltas but the theta/gamma is still a desirable position, selling stock flattens out the delta. If the effect of gamma creates unwanted short deltas, buying stock flattens out the delta.
Trading Volatility Term Structure
There are other reasons for trading calendar spreads besides generating income from theta. If there is skew in the term structure of volatility, which was discussed in Chapter 3, a calendar spread is a way to trade volatility. The tactic is to buy the “cheap” month and sell the “expensive” month.
Selling the Front, Buying the Back
If for a particular stock, the February ATM calls are trading at 50 volatility and the May ATM calls are trading at 35 volatility, a vol-calendar trader would buy the Mays and sell the Februarys. Sounds simple, right? The devil is in the details. We’ll look at an example and then discuss some common pitfalls with vol-trading calendars.
George has been studying the implied volatility of a $164.15 stock. George notices that front-month volatility has been higher than that of the other months for a couple of weeks. There is nothing in the news to indicate immediate risk of extraordinary movement occurring in this example.
George sees that he can sell the 22-day July 165 calls at a 45 percent IV and buy the 85-day September 165 calls at a 38 percent IV. George would like to buy the calendar spread, because he believes the July ATM volatility will drop down to around 38, where the September is trading. If he puts on this trade, he will establish the following position:
What are George’s risks? Because he would be selling the short-term ATM option, negative gamma could be a problem. The greeks for this trade, shown in
Exhibit 11.7
, confirm this. The negative gamma means each dollar of stock price movement causes an adverse change of about 0.09 to delta. The spread’s delta becomes shorter when the stock rises and longer when the stock falls. Because the position’s delta is long 0.369 from the start, some price appreciation may be welcomed in the short term. The stock advance will yield profits but at a diminishing rate, as negative gamma reduces the delta.
EXHIBIT 11.7
10-lot July–September 165 call calendar.
But just looking at the net position greeks doesn’t tell the whole story. It is important to appreciate the fact that long calendar spreads such as this have long vegas. In this case, the vega is +1.522. But what does this number really mean? This vega figure means that if IV rises or falls in both the July and the September calls by the same amount, the spread makes or loses $152 per vol point.
George’s plan, however, is to see the July’s volatility decline to converge with the September’s. He hopes the volatilities of the two months will move independently of each other. To better gauge his risk, he needs to look at the vega of each option. With the stock at $164.15 the vegas are as follows:
If George is right and July volatility declines 8 points, from 46 to 38, he will make $1,283 ($1.604 × 100 × 8).
There are a couple of things that can go awry. First, instead of the volatilities converging, they can diverge further. Implied volatility is a slave to the whims of the market. If the July IV continues to rise while the September IV stays the same, George loses $160 per vol point.
The second thing that can go wrong is the September IV declining along with the July IV. This can lead George into trouble, too. It depends the extent to which the September volatility declines. In this example, the vega of the September leg is about twice that of the July leg. That means that if the July volatility loses eight points while the September volatility declines four points, profits from the July calls will be negated by losses from the September calls. If the September volatility falls even more, the trade is a loser.
IV is a common cause of time-spread failure for market makers. When i in the front month rises, the volatility of the back-months sometimes does as well. When this happens, it’s often because market makers who sold front-month options to retail or institutional buyers buy the back-month options to hedge their short-gamma risk. If the market maker buys enough back-month options, he or she will accumulate positive vega. But when the market sells the front-month volatility back to the market makers, the back months drop, too, because market makers no longer need the back months for a hedge.
Traders should study historical implied volatility to avoid this pitfall. As is always the case with long vega strategies, there is a risk of a decline in IV. Buying long-term options with implied volatility in the lower third of the 12-month IV range helps improve the chances of success, since the volatility being bought is historically cheap.
This can be tricky, however. If a trader looks back on a chart of IV for an option class and sees that over the past six months it has ranged between 20 and 30 but nine months ago it spiked up to, say, 55, there must be a reason. This solitary spike could be just an anomaly. To eliminate the noise from volatility charts, it helps to filter the data. News stories from that time period and historical stock charts will usually tell the story of why volatility spiked. Often, it is a one-time event that led to the spike. Is it reasonable to include this unique situation when trying to get a feel for the typical range of implied volatility? Usually not. This is a judgment call that needs to be made on a case-by-case basis. The ultimate objective of this exercise is to determine: “Is volatility cheap or expensive?”
Buying the Front, Selling the Back
All trading is based on the principle of “buy low, sell high”—even volatility trading. With time spreads, we can do both at once, but we are not limited to selling the front and buying the back. When short-term options are trading at a lower IV than long-term ones, there may be an opportunity to sell the calendar. If the IV of the front month is 17 and the back-month IV is 25, for example, it could be a wise trade to buy the front and sell the back. But selling time spreads in this manner comes with its own unique set of risks.
First, a short calendar’s greeks are the opposite of those of a long calendar. This trade has negative theta with positive gamma. A sideways market hurts this position as negative theta does its damage. Each day of carrying the position is paid for with time decay.
The short calendar is also a short-vega trade. At face value, this implies that a drop in IV leads to profit and that the higher the IV sold in the back month, the better. As with buying a calendar, there are some caveats to this logic.
If there is an across-the-board decline in IV, the net short vega will lead to a profit. But an across-the-board drop in volatility, in this case, is probably not a realistic expectation. The front month tends to be more sensitive to volatility. It is a common occurrence for the front month to be “cheap” while the back month is “expensive.”
The volatilities of the different months can move independently, as they can when one buys a time spread. There are a couple of scenarios that might lead to the back-month volatility’s being higher than the front month. One is high complacency in the short term. When the market collectively sells options in expectation of lackluster trading, it generally prefers to sell the short-term options. Why? Higher theta. Because the trade has less time until expiration, the trade has a shorter period of risk. Because of this, selling pressure can push down IV in the front-month options more than in the back. Again, the front month is more sensitive to changes in implied volatility.
Because volatility has peaks and troughs, this can be a smart time to sell a calendar. The focus here is in seeing the “cheap” front month rise back up to normal levels, not so much in seeing the “expensive” back month fall. This trade is certainly not without risk. If the market doesn’t move, the negative theta of the short calendar leads to a slow, painful death for calendar sellers.
Another scenario in which the back-month volatility can trade higher than the front is when the market expects higher movement after the expiration of the short-term option but before the expiration of the long-term option. Situations such as the expectation of the resolution of a lawsuit, a product announcement, or some other one-time event down the road are opportunities for the market to expect such movement. This strategy focuses on the back-month vol coming back down to normal levels, not on the front-month vol rising. This can be a more speculative situation for a volatility trade, and more can go wrong.
The biggest volatility risk in selling a time spread is that what goes up can continue to go up. The volatility disparity here is created by hedgers and speculators favoring long-term options, hence pushing up the volatility, in anticipation of a big future stock move. As the likely date of the anticipated event draws near, more buyers can be attracted to the market, driving up IV even further. Realized volatility can remain low as investors and traders lie in wait. This scenario is doubly dangerous when volatility rises and the stock doesn’t move. A trader can lose on negative theta and lose on negative vega.
A Directional Approach
Calendar spreads are often purchased when the outlook for the underlying is neutral. Sell the short-term ATM option; buy the long-term ATM option; collect theta. But with negative gamma, these trades are never really neutral. The delta is constantly changing, becoming more positive or negative. It’s like a rubber band: at times being stretched in either direction but always demanding a pull back to the strike. When the strike price being traded is not ATM, calendar spreads can be strategically traded as directional plays.
Buying a calendar, whether using calls or puts, where the strike price is above the current stock price is a bullish strategy. With calls, the positive delta of the long-term out-of-the-money (OTM) call will be greater than the negative delta of the short-term OTM call. For puts, the positive delta of the short-term in-the-money (ITM) put will be greater than the negative delta of the long-term ITM put.
Just the opposite applies if the strike price is below the current stock price. The negative delta of the short-term ITM call is greater than the positive delta of the long-term ITM call. The negative delta of the long-term OTM put is greater than the positive delta of the short-term OTM put.
When the position starts out with either a positive or negative delta, movement in the direction of the delta is necessary for the trade to be profitable. Negative gamma is also an important strategic consideration. Stock-price movement is needed, but not too much.
Buying calendar spreads is like playing outfield in a baseball game. To catch a fly ball, an outfielder must focus on both distance and timing. He must gauge how far the ball will be hit and how long it will take to get there. With calendars, the distance is the strike price—that’s where the stock needs to be—and the time is the expiration day of the short month’s option: that’s when it needs to be at the target price.
For example, with Wal-Mart (WMT) at $48.50, a trader, Pete, is looking for a rise to about $50 over the next five or six weeks. Pete buys the August–September call calendar. In this example, August has 39 days until expiration and September has 74 days.
Exactly what does 50 cents buy Pete? The stock price sitting below the strike price means a net positive delta. This long time spread also has positive theta and vega. Gamma is negative.
Exhibit 11.8
shows the specifics.
EXHIBIT 11.8
10-lot Wal-Mart August–September 50 call calendar.
The delta of this trade, while positive, is relatively small with 39 days left until August expiration. It’s not rational to expect a quick profit if the stock advances faster than expected. But ultimately, a rise in stock price is the goal. In this example, Wal-Mart needs to rise to $50, and timing is everything. It needs to be at that price in 39 days. In the interim, a move too big and too fast in either direction hurts the trade because of negative gamma. Starting with Wal-Mart at $48.50, delta/gamma problems are worse to the downside.
Exhibit 11.9
shows the effects of stock price on delta, gamma, and theta.
EXHIBIT 11.9
Stock price movement and greeks.
If Wal-Mart moves lower, the delta gets more positive, racking up losses at a higher rate. To add to Pete’s woes, theta becomes less of a benefit as the stock drifts lower. At $47 a share, theta is about flat. With Wal-Mart trading even lower than $47, the positive theta of the August call is overshadowed by the negative theta of the September. Theta can become negative, causing the position to lose value as time passes.
A big move to the upside doesn’t help either. If Wal-Mart rises just a bit, the −0.323 gamma only lessens the benefit of the 0.563 delta. But above $50, negative gamma begins to cause the delta to become increasingly negative. Theta begins to wither away at higher stock prices as well.
The place to be is right at $50. The delta is flat and theta is highest. As long as Wal-Mart finds its way up to this price by the third Friday of August, life is good for Pete.
The In-or-Out Crowd
Pete could just as well have traded the Aug–Sep 50 put calendar in this situation. If he’d been bearish, he could have traded either the Aug–Sep 45 call spread or the Aug–Sep 45 put spread. Whether bullish or bearish, as mentioned earlier, the call calendar and the put calendar both function about the same. When deciding which to use, the important consideration is that one of them will be in-the-money and the other will be OTM. Whether you have an ITM spread or an OTM spread has potential implications for the success of the trade.
The bid-ask spreads tend to be wider for higher-delta, ITM options. Because of this, it can be more expensive to enter into an ITM calendar. Why? Trading options with wider markets requires conceding more edge. Take the following options series:
By buying the May 50 calls at 3.20, a trader gives up 0.10 of theoretical edge (3.20 is 0.10 higher than the theoretical value). Buying the put at 1.00 means buying only 0.05 over theoretical.
Because a calendar is a two-legged spread, the double edge given up by trading the wider markets of two in-the-money options can make the out-of-the-money spread a more attractive trade. The issue of wider markets is compounded when rolling the spread. Giving up a nickel or a dime each month can add up, especially on nominally low-priced spreads. It can cut into a high percentage of profits.
Early assignment can complicate ITM calendars made up of American options, as dividends and interest can come into play. The short leg of the spread could get assigned before the expiration date as traders exercise calls to capture the dividend. Short ITM puts may get assigned early because of interest.
Although assignment is an undesirable outcome for most calendar spread traders, getting assigned on the short leg of the calendar spread may not necessarily create a significantly different trade. If a long put calendar, for example, has a short front-month put that is so deep in-the-money that it is likely to get assigned, it is trading close to a 100 delta. It is effectively a long stock position already. After assignment, when a long stock position is created, the resulting position is long stock with a deep ITM long put—a fairly delta-flat position.
Double Calendars
Definition
: A double calendar spread is the execution of two calendar spreads that have the same months in common but have two different strike prices.
Example
Sell 1 XYZ February 70 call
Buy 1 XYZ March 70 call
Sell 1 XYZ February 75 call
Buy 1 XYZ March 75 call
Double calendars can be traded for many reasons. They can be vega plays. If there is a volatility-time skew, a double calendar is a way to take a position without concentrating delta or gamma/theta risk at a single strike.
This spread can also be a gamma/theta play. In that case, there are two strikes, so there are two potential focal points to gravitate to (in the case of a long double calendar) or avoid (in the case of a short double calendar).
Selling the two back-month strikes and buying the front-month strikes leads to negative theta and positive gamma. The positive gamma creates favorable deltas when the underlying moves. Positive or negative deltas can be covered by trading the underlying stock. With positive gamma, profits can be racked up by buying the underlying to cover short deltas and subsequently selling the underlying to cover long deltas.
Buying the two back-month strikes and selling the front-month strikes creates negative gamma and positive theta, just as in a conventional calendar. But the underlying stock has two target price points to shoot for at expiration to achieve the maximum payout.
Often double calendars are traded as IV plays. Many times when they are traded as IV plays, traders trade the lower-strike spread as a put calendar and the higher-strike spread a call calendar. In that case, the spread is sometimes referred to as a
strangle swap
. Strangles are discussed in Chapter 15.
Two Courses of Action
Although there may be many motivations for trading a double calendar, there are only two courses of action: buy it or sell it. While, for example, the trader’s goal may be to capture theta, buying a double calendar comes with the baggage of the other greeks. Fully understanding the interrelationship of the greeks is essential to success. Option traders must take a holistic view of their positions.
Let’s look at an example of buying a double calendar. In this example, Minnesota Mining & Manufacturing (MMM) has been trading in a range between about $85 and $97 per share. The current price of Minnesota Mining & Manufacturing is $87.90. Economic data indicate no specific reasons to anticipate that Minnesota Mining & Manufacturing will deviate from its recent range over the next month—that is, there is nothing in the news, no earnings anticipated, and the overall market is stable. August IV is higher than October IV by one volatility point, and October implied volatility is in line with 30-day historical volatility. There are 38 days until August expiration, and 101 days until October expiration.
The Aug–Oct 85–90 double calendar can be traded at the following prices:
Much like a traditional calendar spread, the price points cannot be definitively plotted on a P&(L) diagram. What is known for certain is that at August expiration, the maximum loss is $3,200. While it’s comforting to know that there is limited loss, losing the entire premium that was paid for the spread is an outcome most traders would like to avoid. We also know the maximum gains occur at the strike prices; but not exactly what the maximum profit can be.
Exhibit 11.10
provides an alternative picture of the position that is useful in managing the trade on a day-to-day basis.
EXHIBIT 11.10
10-lot Minnesota Mining & Manufacturing Aug–Oct 85–90 double call calendar.
These numbers are a good representation of the position’s risk. Knowing that long calendars and long double calendars have maximum losses at the expiration of the short-term option equal to the net premiums paid, the max loss in this example is 3.20. Break-even prices are not relevant to this position because they cannot be determined with any certainty. What is important is to get a feel for how much movement can hurt the position.
To make $19 a day in theta, a −0.468 gamma must be accepted. In the long run, $1 of movement is irrelevant. In fact, some movement is favorable because the ideal point for MMM to be at, at August expiration is either $85 or $90. So while small moves are acceptable, big moves are of concern. The negative gamma is an illustration of this warning.
The other risk besides direction is vega. A positive 1.471 vega means the calendar makes or loses about $147 with each one-point across-the-board change in implied volatility. Implied volatility is a risk in all calendar trades. Volatility was one of the criteria studied when considering this trade. Recall that the August IV was one point higher than the October and that the October IV was in line with the 30-day historical volatility at inception of the trade.
Considering the volatility data is part of the due diligence when considering a calendar or a double calendar. First, the (slightly) more expensive options (August) are being sold, and the cheaper ones are being bought (October). A study of the company reveals no news to lead one to believe that Minnesota Mining & Manufacturing should move at a higher realized volatility than it currently is in this example. Therefore, the front month’s higher IV is not a red flag. Because the volatility of the October option (the month being purchased) is in line with the historical volatility, the trader could feel that he is paying a reasonable price for this volatility.
In the end, the trade is evaluated on the underlying stock, realized volatility, and IV. The trade should be executed only after weighing all the available data. Trading is both cerebral and statistical in nature. It’s about gaining a statistically better chance of success by making rational decisions.
Diagonals
Definition
: A diagonal spread is an option strategy that involves buying one option and selling another option with a different strike price and with a different expiration date. Diagonals are another strategy in the time spread family.
Diagonals enable a trader to exploit opportunities similar to those exploited by a calendar spread, but because the options in a diagonal spread have two different strike prices, the trade is more focused on delta. The name
diagonal
comes from the fact that the spread is a combination of a horizontal spread (two different months) and a vertical spread (two different strikes).
Say it’s 22 days until January expiration and 50 days until February expiration. Apple Inc. (AAPL) is trading at $405.10. Apple has been in an uptrend heading toward the peak of its six-month range, which is around $420. A trader, John, believes that it will continue to rise and hit $420 again by February expiration. Historical volatility is 28 percent. The February 400 calls are offered at a 32 implied volatility and the January 420 calls are bid on a 29 implied volatility. John executes the following diagonal:
Exhibit 11.11
shows the analytics for this trade.
EXHIBIT 11.11
Apple January–February 400–420 call diagonal.
From the presented data, is this a good trade? The answer to this question is contingent on whether the position John is taking is congruent with his view of direction and volatility and what the market tells him about these elements.
John is bullish up to August expiration, and the stock in this example is in an uptrend. Any rationale for bullishness may come from technical or fundamental analysis, but techniques for picking direction, for the most part, are beyond the scope of this book. Buying the lower strike in the February option gives this trade a more positive delta than a straight calendar spread would have. The trader’s delta is 0.255, or the equivalent of about 25.5 shares of Apple. This reflects the trader’s directional view.
The volatility is not as easy to decipher. A specific volatility forecast was not stated above, but there are a few relevant bits of information that should be considered, whether or not the trader has a specific view on future volatility. First, the historical volatility is 28 percent. That’s lower than either the January or the February calls. That’s not ideal. In a perfect world, it’s better to buy below historical and sell above. To that point, the February option that John is buying has a higher volatility than the January he is selling. Not so good either. Are these volatility observations deal breakers?
A Good Ex-Skews
It’s important to take skew into consideration. Because the January calls have a higher strike price than the February calls, it’s logical for them to trade at a lower implied volatility. Is this enough to justify the possibility of selling the lower volatility? Consider first that there is some margin for error. The bid-ask spreads of each of the options has a volatility disparity. In this case, both the January and February calls are 10 cents wide. That means with a January vega of 0.34 the bid-ask is about 0.29 vol points wide. The Februarys have a 0.57 vega. They are about 0.18 vol points wide. That accounts for some of the disparity. Natural vertical skew accounts for the rest of the difference, which is acceptable as long as the skew is not abnormally pronounced.
As for other volatility considerations, this diagonal has the rather unorthodox juxtaposition of positive vega and negative gamma seen with other time spreads. The trader is looking for a move upward, but not a big one. As the stock rises and Apple moves closer to the 420 strike, the positive delta will shrink and the negative gamma will increase. In order to continue to enjoy profits as the stock rises, John may have to buy shares of Apple to keep his positive delta. The risk here is that if he buys stock and Apple retraces, he may end up negative scalping stock. In other words, he may sell it back at a lower price than he bought it. Using stock to adjust the delta in a negative-gamma play can be risky business. Gamma scalping is addressed further in Chapter 13.
Making the Most of Your Options
The trader from the previous example had a time-spread alternative to the diagonal: John could have simply bought a traditional time spread at the 420 strike. Recall that calendars reap the maximum reward when they are at the shared strike price at expiration of the short-term option. Why would he choose one over the other?
The diagonal in that example uses a lower-strike call in the February than a straight 420 calendar spread and therefore has a higher delta, but it costs more. Gamma, theta, and vega may be slightly lower with the in-the-money call, depending on how far from the strike price the ITM call is and how much time until expiration it has. These, however, are less relevant differences.
The delta of the February 400 call is about 0.57. The February 420 call, however, has only a 0.39 delta. The 0.18 delta difference between the calls means the position delta of the time spread will be only about 0.07 instead of about 0.25 of the diagonal—a big difference. But the trade-off for lower delta is that the February 420 call can be bought for 12.15. That means a lower debit paid—that means less at risk. Conversely, though there is greater risk with the diagonal, the bigger delta provides a bigger payoff if the trader is right.
Double Diagonals
A double diagonal spread is the simultaneous trading of two diagonal spreads: one call spread and one put spread. The distance between the strikes is the same in both diagonals, and both have the same two expiration months. Usually, the two long-term options are more out-of-the-money than the two shorter-term options. For example
Buy 1 XYZ May 70 put
Sell 1 XYZ March 75 put
Sell 1 XYZ March 85 call
Buy 1 XYZ May 90 call
Like many option strategies, the double diagonal can be looked at from a number of angles. Certainly, this is a trade composed of two diagonal spreads—the March–May 70–75 put and the March–May 85–90 call. It is also two strangles—buying the May 70–90 strangle and selling the March 75–85 strangle. One insightful way to look at this spread is as an iron condor in which the guts are March options and the wings are May options.
Trading a double diagonal like this one, rather than a typically positioned iron condor, can offer a few advantages. The first advantage, of course, is theta. Selling short-term options and buying long-term options helps the trader reap higher rates of decay. Theta is the raison d’être of the iron condor. A second advantage is rolling. If the underlying asset stays in a range for a long period of time, the short strangle can be rolled month after month. There may, in some cases, also be volatility-term-structure discrepancies on which to capitalize.
A trader, Paul, is studying JPMorgan (JPM). The current stock price is $49.85. In this example, JPMorgan has been trading in a pretty tight range over the past few months. Paul believes it will continue to do so over the next month. Paul considers the following trade:
Paul considers volatility. In this example, the JPMorgan ATM call, the August 50 (which is not shown here), is trading at 22.9 percent implied volatility. This is in line with the 20-day historical volatility, which is 23 percent. The August IV appears to be reasonably in line with the September volatility, after accounting for vertical skew. The IV of the August 52.50 calls is 1.5 points above that of the September 55 calls and the August 47.50 put IV is 1.6 points below the September 45 put IV. It appears that neither month’s volatility is cheap or expensive.
Exhibit 11.12
shows the trade’s greeks.
EXHIBIT 11.12
10-lot JPMorgan August–September 45–47.50–52.50–55 double diagonal.
The analytics of this trade are similar to those of an iron condor. Immediate directional risk is almost nonexistent, as indicated by the delta. But gamma and theta are high, even higher than they would be if this were a straight September iron condor, although not as high as if this were an August iron condor.
Vega is positive. Surely, if this were an August or a September iron condor, vega would be negative. In this example, Paul is indifferent as to whether vega is positive or negative because IV is fairly priced in terms of historical volatility and term structure. In fact, to play it close to the vest, Paul probably wants the smallest vega possible, in case of an IV move. Why take on the risk?
The motivation for Paul’s double diagonal was purely theta. The volatilities were all in line. And this one-month spread can’t be rolled. If Paul were interested in rolling, he could have purchased longer-term options. But if he is anticipating a sideways market for only the next month and feels that volatility could pick up after that, the one-month play is the way to go. After August expiration, Paul will have three choices: sell his Septembers, hold them, or turn them into a traditional iron condor by selling the September 47.50s and 52.50s. This depends on whether he is indifferent, expects high volatility, or expects low volatility.
The Strength of the Calendar
Spreads in the calendar-spread family allow traders to take their trading to a higher level of sophistication. More basic strategies, like vertical spreads and wing spreads, provide a practical means for taking positions in direction, realized volatility, and to some extent implied volatility. But because calendar-family spreads involve two expiration months, traders can take positions in the same market variables as with these more basic strategies and also in the volatility spread between different expiration months. Calendar-family spreads are veritable volatility spreads. This is a powerful tool for option traders to have at their disposal.
Note
1
. Advanced hedging techniques are discussed in subsequent chapters.