Reading a quote drill-down

The first time someone opens a quote drill-down on RateStack, they see twelve to twenty rows of numbers and labels and ask, reasonably, "what am I looking at?" This guide walks through a real example — a conventional 30-year purchase on a primary single-family home — and explains every line.

The basics

A quote has three parts: the result (final price, note rate, lock period), the rule trace (ordered list of rules that fired), and the metadata (ratesheet version, investor, program code, correlationId). The trace is the part that matters most.

Anatomy of a trace

Each row in the trace is a single rule firing, in the order it ran. A row carries:

• Rule id — opaque database identifier; useful for support tickets.
• Description — human-readable summary of the rule.
• Condition matched — the predicate that fired (e.g., FICO between 740 and 759).
• Combine strategy — SUM, MAX, MIN, OVERRIDE, REPLACE_DIMENSION.
• Value contributed — signed; positive raises price, negative lowers it.
• Running cumulative — the price after this rule fires.

Reading the example

Consider this trimmed trace:

01  Base price (rate 6.625)         +100.625   = 100.625
02  LLPA: FICO 740-759 / LTV 75-80   -0.250    = 100.375
03  Adj: Primary, Purchase           +0.000    = 100.375
04  SRP: Conv 30YR (investor 42)     +0.500    = 100.875
05  Margin layer: branch standard    -0.250    = 100.625
06  Margin layer: org adjustment     -0.125    = 100.500
─────────────────────────────────────────────────────────
   Final price                                  100.500

Row 1 is the base price at the requested rate, lifted straight from the ratesheet grid. Row 2 is an LLPA (loan-level pricing adjustment) — the FICO/LTV grid's contribution. Row 3 is an explicit no-op, captured for audit completeness. Row 4 is an SRP (servicing released premium) the investor is paying for the loan. Rows 5 and 6 are margin layers — your comp/margin hierarchy.

What to look for

When the price feels off, the trace tells you why in one of three ways:

• Big single line — usually a punitive LLPA. FICO band, LTV band, or property-type adjustment is the most common culprit.
• Many small lines that add up — your margin layer is heavier than expected. Walk the comp/margin hierarchy.
• An OVERRIDE row that resets the running cumulative — an investor- or program-level override fired. Rare but worth noticing when you see it.

The drill-down view

The workspace renders the trace as an expandable card per rule, so you can collapse the noise and focus on the rule you're reasoning about. Click any row for the source rule definition (operators, ranges, target field) and the source ratesheet version (so you can check the grid directly).

Showing the trace to compliance

The trace is the compliance answer. When auditors ask "why did this loan price this way?" the trace is the response — not a paraphrase of it. Some teams export it to PDF; others link directly to the workspace via the correlationId. Either approach works.

Showing the trace to a borrower

Most borrowers do not want a 20-row trace. They want a one-paragraph explanation. The pricing API exposes a summary builder that condenses the trace into the one or two adjustments that materially moved the price, with their human-readable descriptions. Good enough for a borrower call, rigorous enough that you don't have to memorize anything.