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The Ultimate Guide to Financial Modeling Best Practices - Wall Street Prep

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The Ultimate Guide to Financial Modeling et
Practice
Introduction
Like man computer programmer, people who uild nancial model can get quite opinionated aout the “right wa” to do it.
In fact, there i urpriingl little conitenc acro Wall treet around the tructure of nancial model. One reaon i that model can var widel in
purpoe. For example, if our tak wa to uild a dicounted cah ow (DCF) model to e ued in a preliminar pitch ook a a valuation for one of 5
potential acquiition target, it would likel e a wate of time to uild a highl complex and feature-rich model. The time required to uild a uper
complex DCF model in’t juti ed given the model’ purpoe.
On the other hand, a leveraged nance model ued to make thouand of loan approval deciion for a variet of loan tpe under a variet of
cenario neceitate a great deal of complexit.
Undertanding the purpoe of the model i ke to determining it optimal tructure. There are two primar determinant of a model’ ideal
tructure: granularit and exiilit. Let’ conider the following 5 common nancial model:
Model
One page DCF
Purpoe
Granularit
Flexiilit
Ued in a u ide pitch ook to provide a
Low. all-park valuation range
Low. Not reuale without tructural modi cation. Will e ued in
valuation range for one of everal potential
i u cient) / mall. ntire
a peci c pitch and circulated etween jut 1-3 deal team memer.
acquiition target.
anali can t on one
workheet < 300 row)
Full
Ued to value target compan in a fairne
integrated
opinion preented to the acquiring compan
Medium
for ue in the fairne opinion and circulated etween deal time
DCF
oard of director
memer.
Comp model
Ued a the tandard model  the entire
template
indutrial team at a ulge racket ank
Medium
Low. Not reuale without tructural modi cation. Will e tailored
High. Reuale without tructural modi cation. A template to e
ued for a variet of pitche and deal  man analt and
aociate, poil other takeholder. Will e ued  people with
varing level of xcel kill.
Retructuring
uilt peci call for a multinational
model
corporation to tre tet the impact of
High
Medium. ome re-uailit ut not quite a template. Will e ued 
oth the deal team and counterpart at the client rm.
elling 1 or more uinee a part of a
retructuring advior engagement
Leveraged
nance
model
Ued in the loan approval proce to analze
loan performance under variou operating
High
High. Reuale without tructural modi cation. A template to e
ued group wide.
cenario and credit event
Financial model granularit
A critical determinant of the model’ tructure i granularit. Granularit refer to how detailed a model need to e. For example, imagine ou are
taked with performing an LO anali for Dine. If the purpoe i to provide a ack-of-the-envelope oor valuation range to e ued in a preliminar
pitch ook, it might e perfectl appropriate to perform a “high level” LO anali, uing conolidated data and making ver imple aumption for
nancing.
If, however, our model i a ke deciion making tool for nancing requirement in a potential recapitalization of Dine, a far higher degree of
accurac i incredil important. The di erence in thee two example might involve thing like:
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Forecating revenue and cot of good egment  egment and uing price-per-unit and #-unit-old driver intead of aggregate forecat
Forecating nancial acro di erent uine unit a oppoed to looking onl at conolidated nancial
Analzing aet and liailitie in more detail (i.e. leae, penion, PP&, etc.)
reaking out nancing into variou tranche with more realitic pricing
Looking at quarterl or monthl reult intead of annual reult
Practicall peaking, the more granular a model, the longer and more di cult it will e to undertand. In addition, the likelihood of error grow
exponentiall  virtue of having more data. Therefore, thinking aout the model’ tructure — from the laout of the workheet to the laout of
individual ection, formula, row and column — i critical for granular model. In addition, integrating formal error and “integrit” check can
mitigate error.
Financial model exiilit
The other main determinant for how to tructure a model i it required exiilit. A model’ exiilit tem from how often it will e ued,  how
man uer, and for how man di erent ue. A model deigned for a peci c tranaction or for a particular compan require far le exiilit than
one deigned for heav reue (often called a template).
A ou can imagine, a template mut e far more exile than a compan peci c or “tranaction peci c model. For example, a that ou are taked
with uilding a merger model. If the purpoe of the model i to analze the potential acquiition of Dine  Apple, ou would uild in far le
functionalit than if it purpoe wa to uild a merger model that can handle an two companie. peci call, a merger model template might require
the following item that are not required in the deal-peci c model:
1. Adjutment to acquirer currenc
2. Dnamic calendarization (to et target’ nancial to acquirer’ cal ear)
3. Placeholder for a variet of income tatement, alance heet and cah ow tatement line item that don’t appear on Dine or Apple nancial
4. Net operating lo anali (neither Dine or Apple have NOL)
Together, granularit and exiilit largel determine the tructural requirement of a model. tructural requirement for model with low granularit
and a limited uer ae are quite low. Rememer, there i a trade-o to uilding a highl tructured model: time. If ou don’t need to uild in ell and
whitle, don’t. A ou add granularit and exiilit, tructure and error proo ng ecome critical.
The tale elow how the granularit/ exiilit level of common invetment anking model.
High exiilit
High granularit
Leveraged nance credit model
Low exiilit
Integrated LO model
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Merger model template “one ize t all”
Integrated DCF model
Integrated Merger Model
Integrated operating model
Low granularit
Trading comp template
“ack of the envelope” accretion/dilution model
Tranaction comp template
DCF “one pager”
LO “one pager”
imple operating model
Financial model preent-ailit
Regardle of granularit and exiilit, a nancial model i a tool deigned to aid deciion making. Therefore, all model mut have clearl preented
output and concluion. ince virtuall all nancial model will aid in deciion-making within a variet of aumption and forecat, an e ective
model will allow uer to eail modif and enitize a variet of cenario and preent information in a variet of wa.
Now that we have etalihed a imple framework for tructuring model, it’ time to dicu peci c feature of model architecture, error proo ng,
exiilit and preentation.
Financial model tructure
elow, we la out the ke element of an e ectivel tructured model, mot of which will go a long to wa to improve the model’ tranparenc. A a
model ecome more complex (due to higher granularit and exiilit), it naturall ecome le tranparent. The et practice elow will help to x
thi.
Formatting
Color coding
Jut aout everone agree that color coding cell aed on whether it hold a hard coded numer or a formula i critical. Without color coding, it i
extremel di cult to viuall ditinguih etween cell that hould e modi ed and cell that hould not ( i.e. formula). Well uilt model will further
ditinguih etween formula that link to other workheet and workook a well a cell that link to data ervice.
While di erent invetment ank have di erent houe tle, lue i tpicall ued to color input and lack i ued for formula. The tale
elow how our recommended color coding cheme.
Tpe of cell
xcel formula
Color
Hard-coded numer (input)
=1234
lue
Formula (calculation)
=A1*A2
lack
Link to other workheet
=heet2!A1
Green
Link to other le
=[ook2]heet1!$A$1
Red
Link to data provider (i.e. CIQ, Factet)
=CIQ(IQ_TOTAL_RV)
Dark Red
While everone agree that color coding i ver important, keeping up with it can e a pain in native xcel. It’ not ea to format cell aed on
whether the are input or formula, ut it can e done. One option i to ue xcel’ “Go To pecial” (covered in our xcel Crah Coure, which ou can
enroll in here). Alternativel, color coding i dramaticall impli ed with a third part xcel add-in like Macaacu (which i undled with Wall treet
Prep elf-tud product and oot camp enrollment), Capital IQ or Factet. Thee tool allow ou to “autocolor” an entire workheet in one click.
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Comment
Inerting comment (hortcut hift F2, ee our ential xcel hortcut Lit) in cell i critical for footnoting ource and adding clarit to data in a
model.
For example, a cell containing an aumption on revenue growth that came from an equit reearch report hould include a comment with a reference
to the reearch report. o how much commenting do ou need? Alwa err on the ide of over commenting. No managing director will ever complain
that a model ha too man comment. Additionall, if ou’re on a conference call and omeone ak how ou came up with the numer in cell AC1238
and ou lank, ou’ll regret not commenting.
ign convention
The deciion on whether to ue poitive or negative ign convention mut e made efore the model i uilt. Model in practice are all over the place
on thi one. The modeler hould chooe from and clearl identif one of the following 3 approache:
Convention 1: All income poitive, all expene negative.
Advantage: logical, conitent, make utotal calculation le error-prone
Diadvantage: Doen’t align with convention ued  pulic ling, % margin calculation appear negative
Convention 2: All expene poitive; non-operating income negative.
Advantage: Conitent with pulic ling, % margin calculation appear poitive
Diadvantage: Negative non-operating income i confuing, utotal calculation are error-prone, proper laeling i critical
Convention 3: All expene poitive except non-operating expene.
Advantage: Avoid negative non-operating income preentation; margin evaluate to poitive
Diadvantage: Preentation not internall conitent. Proper laeling i critical.
Our recommendation i Convention 1. The reduced likelihood of error from eaier utotaling alone make thi our clear choice. In addition, one of
the mot common mitake in modeling i forgetting to witch the ign from poitive to negative or vice vera when linking data acro nancial
tatement. Convention 1,  virtue of eing the mot viil tranparent approach, make it eaier to track down ign-related mitake.
Formula
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Avoid partial input (all model)
Hard coded numer (contant) hould never e emedded into a cell reference. The danger here i that ou’ll likel forget there i an aumption
inide a formula. Input mut e clearl eparated from calculation (ee elow).
One row, one calculation
Mot invetment anking model, like the 3-tatement model, rel on hitorical data to drive forecat. Data hould e preented from left to right. The
right of the hitorical column are the forecat column. The formula in the forecat column hould e conitent acro the row.
Ue roll-forward (“A” or “cork-crew”) calculation
Roll-forward refer to a forecating approach that connect the current period forecat to the prior period.
Thi approach i ver ueful in adding tranparenc to how chedule are contructed. Maintaining trict adherence to the roll-forward approach
improve a uer’ ailit to audit the model and reduce the likelihood of linking error.
Write good (and imple) formula
There i a temptation when working in xcel to create complicated formula. While it ma feel good to craft a uper complex formula, the oviou
diadvantage i that no one (including the author after eing awa from the model for a it) will undertand it. ecaue tranparenc hould
drive tructure, complicated formula hould e avoided at all cot. A complicated formula can often e roken down into multiple cell and impli ed.
Rememer, Microoft doen’t charge ou extra for uing more cell! o take advantage of that. elow are ome common trap to avoid:
1. implif IF tatement and avoid neted IF
2. Conider uing ag
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implif IF tatement
IF tatement, while intuitive and well undertood  mot xcel uer, can ecome long and di cult to audit. There are everal excellent alternative
to IF that top-notch modeler frequentl ue. The include uing oolean logic along with a variet of reference function, including MAX, MIN, AND,
OR, VLOOKUP, HLOOKUP, OFFT.
elow i a real-world example of how an IF tatement can e impli ed. Cell F298 ue an urplu cah generated during the ear to pa down the
revolver, up until the revolver i full paid down. However, if de cit are generated during the ear, we want the revolver to grow. While an IF tatement
accomplihe thi, a MIN function doe it more elegantl:
Revolver formula uing IF tatement
Revolver formula uing MIN
The revolver formula uing MIN a an alternative to IF alo hold up etter when additional complexit i required. Imagine that there’ a limit on
annual revolver draw of $50,000. Look at how we have to modif oth formula to accommodate thi:
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Revolver formula using IF statement
Revolver formula uing MIN
While oth formula are challenging to audit, the formula uing IF tatement i more di cult to audit and i more vulnerale to getting completel out
of hand with additional modi cation. It ue neted (or emedded) IF tatement, which our feele human rain have a hard time with once there’
more than one or two.
Fortunatel, xcel ha made thi a it eaier in 2016 with the introduction of the IF function, ut our preference for reling on more elegant function
remain. We pend a lot of time in our xcel Crah Coure going over the man wa “IF alternative” function can e ued to power-charge xcel.
Reduce date-related formula complexit uing ag
Flag refer to a modeling technique mot ueful for modeling tranition acro phae of a compan, project or tranaction over time without violating
the “one row/one calculation” conitenc rule. Imagine ou’re uilding a model for a compan that’ contemplating ankruptc. ach phae of the
retructuring proce ha it own ditinct orrowing and operating characteritic.
In our example elow, the compan’ revolver “freeze” once it goe into ankruptc and a new tpe of orrowing (“DIP”) act a the new revolver until
the compan emerge from ankruptc. Additionall, a new “xit” facilit replace the DIP. We inert 3 “ ag” in row 8-10 to output “TRU/FAL”
aed on the phae we’re in. Thi enale u to uild ver imple, conitent formula for each revolver without having to emed IF tatement into
each calculation.
In cell F16 the formula i =F13*F8. Whenever ou appl an operator (like multiplication) on a TRU, the TRU i treated like a “1” while a FAL i treated
like a “0.” Thi mean that the pre-ankruptc revolver i the de facto revolver when the pre-ankruptc ag evaluate to TRU and ecome 0 once the
ag evaluate to FAL (tarting in column I in our example elow).
The main ene t i that with the ue of jut an extra 3 row, we’ve avoided having to inert an ort of conditional tet within the calculation. The
ame applie to the formula in row 20 and 204 — the ag have prevented a lot of extra code.
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Name and named range
Another wa man modeler reduce formula complexit i  uing name and named range. We trongl caution againt uing name and named
range. A ou’re proal eginning to ene, there i alwa ome kind of tradeo with xcel. In the cae of name, the tradeo i that when ou
name a cell, ou no longer know exactl where it i without going to the name manager. In addition, unle ou are proactivel deleting name (ou
aren’t), xcel will retain thee name even when ou delete the named cell. The reult i that a le ou’re uing toda to uild a DCF contain dozen of
phantom name from prior verion of the model, leading to warning meage and confuion.
Don’t calculate on the alance heet — link from upporting chedule.
In invetment anking, our nancial model will frequentl involve nancial tatement. Ideall, our calculation are done in chedule eparate from
the output ou’re working toward. For example, it’ preferale that ou don’t perform an calculation on the model’ alance heet. Intead, alance
heet forecat hould e determined in eparate chedule and linked into the alance heet a illutrated elow. Thi conitenc help in the
tranparenc and auditing of a model.
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How to reference cell
Never re-enter the ame input in di erent place
For example, if ou’ve inputted a compan name in the rt workheet of the model, reference that workheet name — don’t re-tpe it into the other
workheet. The ame goe for ear and date entered into a column header or a dicount rate aumption ued in a variet of di erent place in the
model. A more utle example of thi i hard coding utotal or P when ou can calculate it. In other word, calculate whenever poile.
Alwa link directl to a ource cell a it i more di
cult to audit “dai chained” data
The one major exception to thi i when “traight-lining” ae period aumption. For thi, go ahead and dai chain. The reaon i that traightlining ae period aumption i an implicit aumption, which can change, thu making it poile for certain ear in the forecat to ultimatel end
of with di erent aumption than other ear.
Avoid formula that contain reference to multiple workheet
Compare the two image elow. It i more di cult to audit the formula in the rt image ecaue ou’ll need to ounce around to di erent workheet
to view the precedent cell. Whenever poile, ring the data from other workheet into the active workheet where the calculation i made.
Link aumption into tandalone cell in the calculation and output heet
If ou’re working with larger model and ou have aumption that need to e referenced from a eparate workheet, conider linking aumption
directl into the workheet where ou’re uing them, and color code them a a ditinct workheet reference link. In other word, don’t have an input
reference emedded into a calculation (i.e. =D13*input!C7). Intead, ue a clean reference =input!C7 and a eparate cell for the calculation. While thi
create a redundant cell reference, it preerve the viual audit-ailit of the model ta and reduce the likelihood of error.
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Avoid linking le
xcel allow ou to link to other xcel le, ut other might not have acce to the linked-to le, or thee le ma get inadvertentl moved.
Therefore, avoid linking to other le whenever poile. If linking to other le i a mut, e vigilant aout color coding all cell reference to other le.
Workheet
One long heet eat man hort heet
A long workheet mean a lot of crolling and le viual compartmentalizing of ection. On the other hand, multiple workheet igni cantl
increae the likelihood of linking error. There’ no hard and fat rule aout thi, ut the general ia hould e toward a longer heet over multiple,
horter workheet. The danger of mi-linking acro workheet i quite real and hard to mitigate, while the iue of cumerome crolling and lack
of compartmentalization aociated with long workheet can e draticall mitigated with xcel’ plit creen functionalit, clear header and link
from a cover heet or tale of content.
Don’t ‘hide’ row — ‘group’ them (and do it paringl)
A model often ha row with data and calculation that ou do not want to how when the model i printed or when ou pate the data into a
preentation. In thi ituation, it’ often tempting to hide row and column for a “cleaner” preentation of reult. The danger i that when the model
i paed around, it i ver ea to mi (and potentiall pate over) the hidden data.
Keeping input (aumption) together (for high-granularit model)
Nearl ever nancial modeling expert recommend a tandard that iolate all of the model’ hard-coded aumption (thing like revenue growth,
WACC, operating margin, interet rate, etc…) in one clearl de ned ection of a model — tpicall on a dedicated ta called ‘input.’ Thee hould
never e commingled with the model’ calculation (i.e. alance heet chedule, the nancial tatement) or output (i.e. credit and nancial ratio,
chart and ummar tale). In other word, think of a model a compried of three clearl identi ed and phicall eparated component:
Aumption → Calculation → Output
Advantage:
Conitent, reliale architecture: Once a model i uilt, the uer ha onl one place the need to go to change an aumption. Thi create a
conitent ditinction etween area in the model that the uer work in v. area the computer work in.
rror mitigation: toring all aumption in one place make it far le likel that ou’ll forget to remove old aumption from a prior anali and
inadvertentl ring them into a new anali.
Yet depite thee advantage, thi practice ha never een widel adopted in invetment anking.
One reaon i impl poor practice. ome model would clearl ene t from an input/calculation/output eparation, ut are often uilt with
no forethought given to tructure. Imagine uilding a houe without an pre-planning. ure, ou’ll avoid the pain of all that planning, ut ou’ll
encounter unforeeen prolem and end up redoing work or adding complexit  working around what’ alread een done. Thi prolem i rampant
in invetment anking model.
Another reaon i that man invetment anking model are impl not granular enough to merit the additional audit trail and legwork. The anale
anker perform are often roader than the are deep. For example, a pitch ook might preent a valuation uingWall
4 ditreet
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none of them will e overl granular. Common invetment anking anale like accretion dilution model, LO model, operating model and DCF
model uuall don’t delve into detail eond the limit of pulic ling and aic forecating. In thi cae, moving ack and forth from input to
calculation to output ta i unnecearil cumerome. A long a ou’re diligent aout color coding, placing aumption on the ame heet and right
elow calculation i preferale in maller model ecaue our aumption are viuall right next to the output, making it ea to ee what’ driving
what.
The other conideration i the numer of a model’ uer. The advantage of the “input together” approach grow with the numer of a model’
intended uer. When ou have man uer, our model will inevital e ued  people with a wide range of modeling pro cienc. In thi cae, a
conitent and reliale tructure that prevent uer from getting into the gut of the model will reduce error. In addition, it will alo reduce
the amount of time a uer ha to pend in the model — a uer can impl locate the area for input, ll them in, and the model (in theor) will work.
That aid, depite attempt  I team to tandardize model, man invetment anking model are eentiall “one-o ” that get materiall modi ed
for each new ue. Aide from comp model which lend themelve to ecoming template, mot model are ued primaril  their original author
(uuall an analt and aociate) who undertand the model well.
The ottom line on keeping input all together
Unfortunatel, there’ no etalihed enchmark for when it make ene to eparate out aumption. The ideal approach depend on the cope and
goal of the model. For a imple 1-page dicounted cah ow anali not intended for frequent reue, it i preferale to emed input throughout the
page. However, for a large full-integrated LO model with man det tranche to e ued a group-wide template, the ene t of keeping all input
together will outweigh the cot.
No pacer column etween data
levator jump
In long workheet, dedicating the leftmot column for placing an “x” or another character at the tart of chedule will make it ea to quickl navigate
from ection to ection.
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Annual v quarterl data (periodicit)
Mot invetment anking model are either quarterl or annual. For example, a U.. equit reearch earning model will alwa e a quarterl model
ecaue one of it ke purpoe i to forecat upcoming earning, which are reported  rm quarterl. imilarl, a retructuring model i uuall a
quarterl model (or even a monthl or weekl model) ecaue a ke purpoe of thi model i to undertand the cah ow impact of operational and
nancing change over the next 1-2 ear. On the other hand, a DCF valuation i a long term anali, with at leat 4-5 ear of explicit forecat
required. In thi cae, an annual model i appropriate.
There are alo model for which oth quarterl and annual period are ueful. For example, a merger model uuall need a quarterl period ecaue
a ke goal i to undertand the impact of the acquiition on the acquirer’ nancial tatement over the next 2 ear. However, attaching a DCF
valuation to the comined merged companie ma alo e deired. In thi cae, a poile olution i to roll up the quarter into an annual model and
extend thoe annual forecat further out.
When determining a model’ periodicit, keep in mind the following:
1. The model mut e et up with the mallet unit of time deired, with longer time period eing aggregated (rolled up) from thoe horter time
period. If ou’re uilding an integrated nancial tatement model in which ou want to ee quarterl and annual data, forecat the quarterl data
rt.
2. Keep the quarterl and annual data in eparate workheet. It i eaier to audit what’ going on when period aren’t commingled. Additionall,
commingling quarterl and annual data in one workheet will either A) force ou to violate the one row/one formula conitenc et practice or )
ou will have to jump through ome craz hoop to maintain the conitenc.
Circularit
Circularit refer to a cell referring to itelf (directl or indirectl). Uuall, thi i an unintentional mitake. In the imple example elow, the uer ha
accidentall included the um total (D5) in the um formula. Notice how xcel ecome confued:
ut ometime a circularit i intentional. For example, if a model calculate a compan’ interet expene aed on a cell that calculate the compan’
revolving det alance, ut that revolving det alance i itelf determined  (among other thing) the compan’ expene (including interet
expene), then we have a circularit:
The logic of uch a calculation i ound: A compan’ orrowing need hould take into account the interet expene. A uch, man invetment
anking model contain intentional circularitie like thee.
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ince unintentional circularit i a mitake to avoid, the uage of intentional circularit in nancial model i controverial. The prolem with intentional
circularit i that a pecial etting mut e elected within ‘xcel Option’ to prevent xcel from miehaving when a circularit exit:
ven with thee etting elected, xcel can ecome untale when handling circularit and often lead to a model “lowing up” (i.e. the model hortcircuit and populate the preadheet with error), requiring manual intervention to zero out the cell containing the ource of circularit:
While the underling logic for wanting to incorporate a circularit into a model ma e valid, circularit prolem can lead to minute, if not hour, of
wated auditing time tring to locate the ource() of circularit to zero them out. There are everal thing modeler can do to etter cope with
circularit, mot notal the creation of a imple circuit reaker, which create a central place in the model that “reet” an cell containing a circularit
or wrapping an error-trap formula (IFRROR) around the formula that i the ource of the circularit.
Circuit reaker or an IFRROR error-trap
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When uilding an intentional circularit, ou MUT uild a circuit reaker and clearl identif all the circularitie in our model. In our imple example,
we placed a circuit reaker in D17 and altered the formula in D8 o the circularit i zeroed out when the uer witche the reaker to “ON”:
Approach 1: Adding a circuit reaker toggle
An alternative approach i to impl wrap an IFRROR function around the ource of the circuilarit. When the model hort circuit, the IFRROR
function evaluate to the FAL condition and populate the model with 0 automaticall. The primar downide to thi approach i that the make
nding unintentional circularitie harder. That’ ecaue ou can never explicitl turn the reaker on or o – the IFRROR doe it automaticall. That
aid, a long a all circ are handled with an IFRROR function, the model will never low up.
Approach 2: Adding an error trap uing the IFRROR function
ottom line: To circ or not to circ?
Depite the circuit reaker and error trap olution, man elieve it i preferale to impl outlaw all circularit from nancial model. For example, the
wa to altogether avoid the intentional circularit in the example aove i to calculate interet expene uing eginning det alance. For quarterl and
monthl model with minor det uctuation, thi i deirale, ut for an annual model with a large forecated change in det, the “ x” can lead to a
materiall di erent reult. Therefore, we do not elieve in a lanket “an.” Intead, we provide the following imple guideline:
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A circularit i onl OK if all the following condition are met.
1. It i intentional: At rik of tating the oviou, ou mut undertand exactl wh, where, and how the circularit exit. The example decried
aove i the mot common ource of circularit in nancial model.
2. You have “enale iterative calculation” elected in our xcel etting: Thi tell xcel the circularit i intentional and enure xcel doen’t throw
up an error and populate the entire model with random zero everwhere.
3. You have a circuit reaker or error trap formula: A circuit reaker or error trap formula enure that if the le get untale and #DIV/0! tart
populating the model, there i an ea and clear wa to x it.
4. The model will not e hared with xcel novice: Circularitie, even with a circuit reaker, can create confuion for xcel uer not familiar with it.
If the model ou are uilding will e hared with client (or a managing director) that like to get into the model ut are generall unfamiliar with
xcel, avoid the circularit and ave ourelf the headache.
Don’t ue macro
Keep macro to an aolute minimum. Ver few people know how macro work, and ome uer cannot open le that ue macro. ver additional
macro i a tep cloer to making our model a “lack ox.” In invetment anking, thi i never a good thing. The onl macro regularl tolerated in
anking model are print macro.
rror checking
xcel i an amazing tool. Unlike oftware peci call deigned to perform a particular et of tak (i.e. real etate invetment oftware, ookkeeping
oftware), xcel i a lank canva, which make it ea to perform extremel complicated anale and quickl develop invaluale tool to help in
nancial deciion making. The downide here i that xcel anale are onl a good a the model uilder (i.e. “Garage in = garage”). Model error i
aolutel rampant and ha eriou conequence. Let’ reak up the mot common modeling error:
1. ad aumption: If our aumption are fault, the model’ output will e incorrect regardle of how well it i tructured.
2. ad tructure: ven if our model’ aumption are great, mitake in calculation and tructure will lead to incorrect concluion.
The ke to mitigating #1 i to preent reult with clearl de ned range of aumption (cenario and enitivitie) and make the aumption clearl
de ned and tranparent. reaking model out into input→calculation→output help other quickl identif and challenge our
aumption (Addreed in detail in the “Preentation” ection aove). The far more perniciou modeling error i #2 ecaue it’ much more di cult to
nd. A ou might imagine, the prolem grow exponentiall a the model’ granularit increae. Thi i wh uilding error check into our model i a
critical part of model uilding.
uild in error check
The mot common error check in a nancial model i the alance check — a formula teting that aet = liailitie + equit:
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Anone who ha uilt an integrated nancial tatement model know it i quite ea to make a imple mitake that prevent the model from alancing.
The alance check clearl identi e to the uer that a mitake ha een made and further invetigation i required. However, there are man other
area of model that are prone to error and thu could merit error check. While ever model will need it own check, ome of the more common
one include:
nuring ource of fund = ue of fund
nuring the quarterl reult add up to annual reult
Total forecat depreciation expene doe not exceed PP&
Det pa-down doe not exceed outtanding principal
Favor direct calculation over “plug”
elow we how two common wa that uer et up a ource & ue of fund tale in nancial model. In oth approache, the uer accidentall
reference intangile aet. In approach 1, the incorrect data i linked into D37. The model notice that ource do not equal ue and throw an error
meage in D41. The econd (and equall common) approach tructurall et D52 equal to D47 and ue D49 a a plug to enure ource and ue
alwa equal. Which approach do ou think i preferale? If ou gueed the rt approach, ou are correct. The prolem the econd (“plug”) approach
i that ecaue of the mi-linking in D50, the model incorrectl calculate the amount of ecured loan required for the tranaction, and no error i
identi ed.
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Whenever a direct calculation i poile, ue it, along with an error check (i.e. “do ource equal ue?”) intead of uilding plug.
Aggregate error check into one area
Place error check cloe to where the relevant calculation i taking place, ut aggregate all error check into a central ea to ee “error dahoard”
that clearl how an error in the model.
rror trapping
Model that require a lot of exiilit (template) often contain area that a uer ma not need now, ut will need down the road. Thi include extra
line item, extra functionalit, etc. Thi create room for error ecaue xcel i dealing with lank value. Formula like IFRROR (and IRROR),
INUMR, ITXT, ILANK are all ueful function for trapping error, epeciall in template.
Preent-ailit
Cover Page and TOC
When a model i deigned for ue  more than jut the model uilder, include a cover page. Cover page hould include:
1. Compan and/or project name
2. Decription of the model
3. Modeler and team contact information
Include a tale of content when the model i u cientl large to merit it (a good rule of thum i more than 5 workheet).
Workheet deign
Lael workheet  the nature of the anali (i.e. DCF, LO, Fintatement, etc…). Ta hould ow logicall from left to right. When following the
input→calculation→output approach, color the workheet ta aed on thi diviion:
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1. Include the compan name on top left of ever heet
2. Include the heet purpoe, cenario elected (when relevant), cale and currenc prominentl elow the compan name on each heet
3. Page etup for printing: When a heet i too long to t in one page, the top row containing compan name, purpoe of the page, currenc and cale
hould e diplaed on top of each page (elect “row to repeat at top” (Page Laout>Page etup>heet)
4. Include le path, page numer and date in footer
cenario and enitivitie
The purpoe of uilding a model i to provide actionale inight that wan’t otherwie readil viile. Financial model hed light on variet of critical
uine deciion:
How doe an acquiition change the nancial tatement of an acquirer (accretion/dilution)?
What i a compan’ intrinic value?
How much hould an invetor contriute to a project given peci ed return requirement and rik tolerance?
Virtuall all invetment anking model rel on forecating and aumption to arrive at the output preented to client. ecaue aumption are 
de nition uncertain, preenting the nancial model’ output in range and aed on a variet of di erent cenario and enitivitie i critical. In thi
pot aout cenario anali and thi pot aout uing data tale for enitivit anali, we addre the two mot e ective wa to preent nancial
output in nancial model.
Concluion and further reading
We wrote thi guide to provide a framework applicale to invetment anking model. For thoe that want to dive deeper into uilding peci c
invetment anking model, conider enrolling in our aghip nancial modeling program. For thoe that want to get into the weed of modeling
theor, I recommend the following text:
uilding Financial Model  John Tjia
Financial Modeling  imon enninga
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