I'm not 100% sure myself on what exactly it's doing vs a DF, but I'd imagine it's doing somewhat less intra-spread hedging as only the wing is shared vs body+wing in the DF case and seems somewhat condorish.
However, given some basics and some brainstorming:
Fly is the difference of two overlapping calendars:
Code:
SP-SP(1) => 1:2:1 (4 => 4, BF)
a-b
-b+c
a-2b+c
Condor is the difference of two non-overlapping calendars:
Code:
SP-SP(0) => 1:1:1:1 (4 => 4, CF)
a-b
-c+d
a-b-c+d
Condor is also the *sum* of two overlapping flies:
Code:
BF+BF(2) => 1:1:1:1 (8 => 4, CF)
a-2b+c
b-2c+d
a-b-c+d
Double fly is the difference of two overlapping flies:
Code:
BF-BF(2) => 1:3:3:1 (8 => 8, DF)
a-2b+c
-b+2c-d
a-3b+3c-d
Extended double fly is the difference of two overlapping flies (wings only):
Code:
BF-BF(1) => 1:2:0:2:1 => (8 => 6, EF)
a-2b+c
-c+2d-e
a-2b+0c+2d-e
Extended double fly is also the difference of two overlapping condors and the sum of two overlapping double flies:
Code:
CF-CF(3) => 1:2:0:2:1 (8 => 12, EF)
a-b-c+d
-b+c+d-e
a-2b+0c+2d-e
DF+DF(3) => 1:2:0:2:1 (16 => 12, EF)
a-3b+3c-d
b-3c+3d-e
a-2b+0c+2d-e
I guess one would might say that if a condor is the sum of two overlapping flies then similarly an EF/EDF is the sum of two overlapping double flies and if we see "sum" it really means "concurrent" in this context (just like being concurrently long or short outright in two different expirations of the same instrument but with more hedging). I think breaking things down into calendars might make it easier to conceptually visualize (let alone execute):
If we take the sum of two flies example (which results in a condor) and break it down into calendars, it looks like this:
Code:
(a-b)-(b-c) (+fly)
(b-c)-(c-d) (+fly)
(a-b) -(c-d) or +a-b-c+d
Which essentially would be a play on two (almost adjacent) calendars vs each other, or alternatively long the wings and short the body like a fly but in this case the body isn't just 1 exp but 2 adjacent expirations.
Since we know that an EF is also the difference of two condors, using the calendar math (note, I pre-negated the other side so that we always use addition):
Code:
(a-b)-(c-d) (+condor)
-(b-c)+(d-e) (-condor)
(a-b)-(b-c)-(c-d)+(d-e) or +a-2b+0c+2d-e
One kinda notices that there's a bit of chaining between months going on here and that in a way it resembles a "condor of calendars" (the +:-:-:+ relationship) or a "fly of calendars" where the body is not a shared calendar (which results in a double fly) but two adjacent calendars (just like two adjacent outrights in the condor example). This seems conceptually similar to a condor in nature and knowing what we know from the previous example where a condor is the sum of two overlapped flies it now makes a bit more sense why the sum of two double flies creates an extended double fly. To me, it appears to be more condor in nature than a fly (due to the less shared body) so I'd expect there to be similar behavior to a DF in the way a condor can be similar to a fly.
Here's a CL Z17M18Z18M19 DF on the daily:
View attachment 167355
And here's a EF for the same general months:
View attachment 167356
Also, Euribor weekly charts DF:
View attachment 167357
vs EF:
View attachment 167358
Some ED/GE weekly charts (EF):
View attachment 167359
View attachment 167360
BTW, one can also experiment with different takes on where things are overlapped or subtracted from each other, even coming up with things that don't even have a name:
Condor vs condor but using less overlap:
Code:
CF-CF(2) => 1:1:2:2:1:1 (8 => 8, kinda like a DF but no shared legs)
a-b-c+d
-c+d+e-f
a-b-2c+2d+e-f or +(a-b)-2*(c-d)+(e-f)
CF-CF(1) => 1:1:1:0:1:1:1 (8 => 6)
a-b-c+d
-d+e+f-g
a-b-c+0d+e+f-g
Weird fly and condor sums:
Code:
BF+BF(1) => 1:2:2:2:1 (8 => 8)
a-2b+c
c-2d+e
a-2b+2c-2d+e
CF+CF(2) => 1:1:0:0:1:1 (8 => 4, CF [widen center])
a-b-c+d
c-d-e+f
a-b-0c-0d-e+f
CF+CF(1) => 1:1:1:2:1:1:1 (8 => 8)
a-b-c+d
d-e-f+g
a-b-c+2d-e-f+g
I suspect that what's really going on here in all of this is control over the shape of how the body and/or wings are hedged vs normal flies.