Waterfall Inspector for DealStudio
Waterfall Inspector is a step-through debugging tool built into DealStudio, allowing inspection of a deal’s priority-of-payments waterfall period by period — seeing exactly how cash flows through each payment rule, tranche, fee, account, and condition at every step. Think of it as a debugger for the deal: set breakpoints on specific payment rules, advance through the waterfall, and inspect the state of every component along the way.
Overview
When structuring or validating a securitization deal, questions Waterfall Inspector can help answer:
- Does cash flow correctly through the priority of payments?
- Does the waterfall behavior match the deal documents?
- Why did a particular tranche receive (or not receive) a payment in a given period?
- Which conditions or triggers affected the payment allocation?
- How do reserve accounts and fees interact with tranche payments?
The Waterfall Inspector makes this process interactive and visual, letting you step through the waterfall logic one rule at a time.
Getting Started
Prerequisites
Before you can use the Waterfall Inspector, you need:
- A deal set up in DealStudio with a structure (tranches, payment rules, etc.) defined
- Cashflows must be run first — the inspector operates on cashflow results, so you need at least one successful cashflow projection before the inspector will be available
How to launch
- Navigate to your deal in the DealStudio Dashboard
- Click Page Actions (in the top-right area of the dashboard)
- Select Inspect Waterfall
- The inspector opens as a panel at the bottom of your screen
Inspector layout
The Waterfall Inspector opens as a resizable drawer at the bottom of the DealStudio interface. You can:
- Resize the panel by dragging its top edge up or down
- Minimize the panel to temporarily hide it while retaining your inspection state
- Reopen a minimized panel to continue where you left off
- Close the panel to end your inspection session (this clears the inspector state)
Using the Inspector
Breakpoints
Breakpoints let you control which payment rules the inspector stops at as you step through the waterfall. This is useful when you want to skip ahead to the rules you care about rather than stepping through every single one.
| Indicator | Meaning |
|---|---|
| Red dot | Breakpoint is set — the inspector will stop at this payment rule when advancing by breakpoint |
| Gray dot | No breakpoint — this step will be skipped when advancing by breakpoint (but still visited when advancing by priority) |
| Header dot (top of column) | Toggle all breakpoints on or off at once |
You can also mute all breakpoints temporarily using the mute button in the inspector controls. This lets you advance by priority without removing your breakpoint selections.
Navigation
The inspector provides two ways to move through the waterfall:
| Mode | Behavior |
|---|---|
| Advance by priority | Move forward one payment rule at a time, in priority order. Every rule is visited regardless of breakpoints. |
| Advance by breakpoint | Jump forward to the next payment rule where a breakpoint is set, skipping everything in between. |
Changing periods: Use the period selector to jump to a different payment period. The inspector will reset to the beginning of the waterfall for that period.
Starting over: To restart the inspection from the beginning of the current period, close and reopen the inspector, or change the period selection.
Note: Navigation is forward-only in the current version. To revisit an earlier step, restart the inspection for that period.
Data tabs
As you step through the waterfall, the inspector displays the state of each deal component in a set of tabbed views. Each tab updates in real time as you advance through payment rules.
| Tab | What it shows |
|---|---|
| Tranches | Per-tranche cashflow detail with three subtabs: Principal (paydowns, writedowns, shortfalls), Interest (coupon, accrued, shortfall), and Balance Change (beginning/ending balance, factor) |
| Accounts | Reserve, payment, and prefunding account balances — deposits, withdrawals, and running totals at each step |
| Fees | Fee amounts due, paid, and unpaid for each waterfall fee at the current step |
| Conditions | Trigger and condition evaluation results — OC tests, cumulative net loss triggers, delinquency triggers, etc. Shows target values, actual values, and pass/fail status |
| Calculations | Intermediate calculated values used by payment rules — available funds, up-to-cap amounts, and other derived quantities |
| Collateral | Underlying collateral pool summary — balances, prepayment, default, and loss metrics that feed into the waterfall |
Payment rules table
The main inspector view displays the deal’s priority of payments as a table with the following columns:
| Column | Description |
|---|---|
| Breakpoint | Click to set or remove a breakpoint on this rule |
| Priority | The rule’s position in the payment waterfall (1 = highest priority) |
| From | The source of funds for this payment (e.g., Available Funds, Interest Collections) |
| Allocate | How funds are distributed (e.g., sequentially, pro rata) |
| To | The destination — which tranche, account, or fee receives funds |
| Up to cap | Maximum amount that can be allocated under this rule (if applicable) |
| Conditions | Any conditions or triggers that must be met for this rule to execute |
| Payment | The actual dollar amount allocated at this step |
| Should pay | Whether this rule is active given the current period’s conditions |
Frequently Asked Questions
General
What is the Waterfall Inspector?
The Waterfall Inspector is a tool within DealStudio that lets you step through a securitization deal’s priority-of-payments waterfall one rule at a time. At each step, you can see exactly how cash is allocated across tranches, fees, and accounts — and what conditions or triggers are affecting the payment logic.
Where do I find it?
Open your deal in DealStudio, then go to Page Actions → Inspect Waterfall. If you don’t see this option, make sure you have run cashflows on the deal first.
Do I need to run cashflows before using the inspector?
Yes. The Waterfall Inspector requires a completed cashflow projection to operate. Run cashflows from the DealStudio cashflows tab first, then open the inspector.
Can I use the inspector while editing my deal structure?
The inspector is a read-only view of your deal’s waterfall behavior. While the inspector is open, structure editing is available in other parts of the interface, but any changes to your deal structure will require you to re-run cashflows and restart the inspector to see updated results.
Breakpoints & Navigation
How do breakpoints work?
Click the dot next to any payment rule to set a breakpoint (it turns red). When you advance by breakpoint, the inspector jumps to the next rule with a red dot, skipping everything in between. This is useful for large waterfalls where you only want to inspect specific rules.
Can I go backward through the waterfall?
Not in the current version. Navigation is forward-only. To revisit an earlier step, close and reopen the inspector (or change the period), which resets to the beginning of the waterfall for that period.
How do I start over?
Two options:
- Close and reopen the inspector — this clears your state and starts fresh
- Change the period — selecting a different period resets the inspector to the beginning of the waterfall for that period
What does the dot at the top of the breakpoint column do?
It’s a select/deselect all toggle. Click it to set breakpoints on every payment rule at once, or click again to clear all breakpoints.
What does the mute button do?
The mute button temporarily disables all breakpoints without removing them. This lets you advance by priority (one step at a time) without losing your breakpoint selections. Click mute again to re-enable them.
Data & Display
What do the data tabs show?
The tabs display the current state of each deal component at the step you’re inspecting. As you advance through payment rules, the values in each tab update to reflect the cumulative effect of all rules processed so far. See the Data Tabs section above for a full description of each tab.
What does “Should Pay” mean in the payment rules table?
Should Pay indicates whether a payment rule is active for the current period based on the deal’s conditions and triggers. If a condition attached to a rule is not met (e.g., an OC trigger has not been breached), the rule may show “Should Pay: No” even though it appears in the priority of payments.
I see a banner saying my data is stale. What should I do?
This banner appears when your deal configuration has changed since the last cashflow run. The inspector is showing results based on the previous cashflow projection, which may no longer reflect your current deal structure. To resolve this:
- Navigate to the Cashflows tab in DealStudio
- Re-run cashflows with your updated configuration
- Reopen the Waterfall Inspector to see the updated results
Changes that trigger this banner include modifications to scenarios, payment rules, tranche definitions, replines, and other structure elements.
Troubleshooting
| Symptom | What to check |
|---|---|
| Inspect Waterfall option not available in Page Actions | Cashflows have not been run on this deal yet. Run cashflows first, then try again. |
| Inspector opens but shows no data | Verify that the cashflow run completed successfully. Check the Cashflows tab for errors. |
| “Re-run cashflow to reflect the latest projection data” banner | Your deal structure has changed since the last cashflow run. Re-run cashflows and reopen the inspector. |
| “Your cashflow projection has changed, restart the waterfall inspector” banner | Cashflows were re-run while the inspector was open. Close and reopen the inspector to load the new results. |
| Error when entering a period number | The period number may exceed the length of the cashflow projection. Check the total number of periods in your cashflow results and enter a valid period number. |
| Tranche balances not populating | This may be account-specific. Try running cashflows again. If the issue persists, contact dv01 Support with your deal name and account details. |
| Inspector state lost after minimizing | Minimizing retains your state; closing clears it. If your state seems lost, you may have closed rather than minimized. Reopen from Page Actions to start a new session. |
Additional Resources
- Running Securitization Cashflows — how to set up and run cashflow projections for securitized deals
- Cashflow Calculations FAQ — common questions about cashflow assumptions and methodology
- Curve Notation Guide — syntax for CPR, CDR, and severity curves used in cashflow scenarios
Have a question not covered here? Contact dv01 Support — include your deal name and a description of what you’re seeing, and we’ll help you sort it out.
Last updated: 2026-06-11