revenue-model-builder

中文文档：README-zh.md

A bottom-up revenue forecasting framework — turn a driver tree (market_base × penetration × share × price) into an auditable revenue model that aligns to reported totals via a structural residual line. Core engine has zero third-party dependencies (pure Python stdlib), including the Monte Carlo + sensitivity layer.

The design encodes five hard-won modeling rules (see design principles): a structural residual that absorbs un-modeled business, A/B/C data grading for traceability, incremental (not growth-rate) penetration forecasts, a certainty pyramid for prioritizing forecast inputs, and a history-first workflow.

Why

Most open-source finance tooling covers trading / backtesting (zipline, backtrader, QuantLib) or DCF valuation. Driver-based revenue forecasting — decomposing revenue into base × penetration × share × price, what sell-side analysts and PE associates actually do — has almost no open-source presence.

The closest neighbors are TAM/SAM/SOM prompt skills for AI agents (e.g. slgoodrich/agents, deanpeters/Product-Manager-Skills) — they describe the methodology in natural language, but none is a runnable engine. This project is: a minimal, pip-installable encoding of the workflow with the math enforced in code rather than left to a prompt.

A sell-side revenue model lives or dies on whether you can defend every number — "where did this penetration come from? why isn't it higher?" Manual spreadsheets answer that with cryptic comments. revenue-model-builder makes it structural: every driver carries a credibility grade and a source, the residual is a first-class line, and an alignment check catches the classic "back-solved penetration" trap before it poisons the forecast.

How it compares

Core idea

segment_revenue = market_base × penetration × share × price
total_revenue   = Σ(segments) + residual          # residual absorbs un-modeled biz

Unit derivation: base in million units × price in yuan = million yuan (when penetration & share are fractions in [0,1]). So Segment.revenue() returns million yuan by construction.

Install

pip install -e .                  # core engine only (pure stdlib, zero deps)
pip install -e ".[excel]"         # + openpyxl, to render .xlsx output
pip install -e ".[dev]"           # + pytest, to run the test suite

Quick start

Build a model and validate it aligns to reported totals:

from revenue_model import Driver, Segment, RevenueModel, BASE, PENETRATION, SHARE, PRICE

seg = Segment(
    name="cockpit-domestic",
    base=Driver("China passenger car sales", BASE, {2022: 22.0, 2023: 23.0},
                level="A", unit="million units", source="CAAM"),
    penetration=Driver("DMS penetration", PENETRATION, {2022: 0.04, 2023: 0.06},
                       level="B", unit="fraction", source="research institute"),
    share=Driver("market share", SHARE, {2022: 0.10, 2023: 0.12},
                 level="C", unit="fraction", source="estimate"),
    price=Driver("ASP", PRICE, {2022: 600, 2023: 620},
                 level="C", unit="yuan", source="benchmark"),
)
model = RevenueModel("DemoCo", [seg], total_revenue={2022: 110.0, 2023: 215.0})

for r in model.validate_all():
    print(r.year, f"segments={r.segment_sum:.1f}", f"residual={r.residual:.1f}",
          f"({r.residual_ratio:.0%})", r.warnings)

Run the fictional demo (NovaTech, an automotive-AI company — all data fabricated):

python -m revenue_model.demo

Render the model to a formatted .xlsx (needs the [excel] extra):

python -m revenue_model.excel_builder output.xlsx

Monte Carlo & sensitivity

Turn point forecasts into distributions and find out which assumption matters most — pure stdlib, no numpy:

from revenue_model import simulate_model, tornado

# Revenue distribution: sample uncertain drivers, multiply, repeat
mc = simulate_model(model, 2024, {
    "market share": (0.10, 0.18),      # C-grade, wide band
    "ASP": (620, 680),
}, n=20000, seed=0)
print(mc.median, mc.percentiles["p5"], mc.percentiles["p95"])  # P5/median/P95

# Tornado: per-driver bands (NOT a uniform %) -> ranked swing
for it in tornado(seg, 2024, {
    "China passenger car sales": (23.5, 24.5),   # A-grade, narrow
    "DMS penetration": (0.07, 0.12),             # B-grade
    "market share": (0.10, 0.18),                # C-grade, wide
    "ASP": (620, 680),
}):
    print(f"{it.driver:28s} swing {it.swing:.1f}")

Why per-driver bands, not a uniform ±%? Revenue is a product (base × pen × share × price), so perturbing every factor by the same percentage yields identical swings — the tornado would have zero discriminating power. A tornado is only meaningful when each band reflects that driver's real uncertainty: narrow for A-grade hard data, wide for C-grade estimates. (This is why A/B/C grading and sensitivity are linked.)

Stochastic processes (experimental)

Upgrade uniform-sampling Monte Carlo to driver-specific stochastic processes — pure stdlib, no numpy. Prices follow geometric Brownian motion; bounded ratios (penetration, share) follow a logit-OU process that stays in (0, 1); drivers can be correlated via Cholesky.

from revenue_model.stochastic import (
    GBMDriver, LogitOUDriver, CorrelatedBundle, simulate_revenue, logit)

price = GBMDriver("ASP", S0=650.0, mu=0.03, sigma=0.10)                # log-normal price
share = LogitOUDriver("market share", p0=0.14, theta=2.0,
                      mu_bar=logit(0.18), sigma=0.10)                  # bounded, mean-reverting
bundle = CorrelatedBundle([price, share], rho=[[1.0, -0.3], [-0.3, 1.0]])

mc = simulate_revenue(segment, 2024, bundle, n=20000, seed=0)         # -> MCResult
print(mc.median, mc.percentiles["p5"], mc.percentiles["p95"])

See design principles: stochastic layer for the SDEs and why logit-OU keeps bounded ratios bounded.

Experimental — the uniform Monte Carlo above remains the default. See tests/test_stochastic.py for analytic-solution validation (GBM mean, OU stationary variance, induced correlation).

Segment extraction (from annual reports)

Automate the tedious part of segment build-up — pull a segment skeleton (business lines, revenue, share, YoY, margin, a driver-type tag, driver hints) out of an annual report's "main business analysis" text via an LLM. Pure stdlib HTTP (no SDK); the LLM call is injectable, so tests/CI need no API key.

from revenue_model import extract_segments, alignment_check

# text = the "main business analysis" section (extracted upstream via PyMuPDF)
parsed = extract_segments(text, api_key="<your-llm-key>")   # load via secrets manager
print(parsed["segments"])                                   # segment skeletons
print(alignment_check(parsed))                             # Σ + residual ≈ reported total

The output matches the schema in docs/proposal-segment-extraction.md §4. Filling concrete driver values (C-grade estimates) remains a human step — see the proposal's semi-automated boundary (§7). Real-company data must not enter the repo (see DISCLAIMER.md); demos use the fictional NovaTech.

Design principles

Plus a validation layer (triangulation, assumption documentation, S-curves): docs/design-principles.md.

API

Driver(name, kind, values, level="C", unit="", source="")
#   kind ∈ {BASE, PENETRATION, SHARE, PRICE};  level ∈ {"A","B","C"}

Segment(name, base, penetration, share, price)
#   .revenue(year) -> float  (million yuan)

implied_driver(segment, year, target_revenue, solve_kind) -> float
#   calibrate one driver to a known revenue (e.g. reported segment revenue);
#   prefer solve_kind=PRICE/BASE over PENETRATION (avoids the back-solve trap)

RevenueModel(company, segments, total_revenue)
#   .validate(year)  -> YearResult   (segment_revenues, residual, warnings)
#   .validate_all()  -> list[YearResult]

simulate_segment(segment, year, ranges, n=10000, seed=0) -> MCResult
simulate_model(model, year, ranges, n=10000, seed=0)     -> MCResult
#   ranges: {driver_name: (low, high)};  MCResult has mean/median/stdev/percentiles

tornado(segment, year, ranges) -> list[SensitivityItem]   # ranked by swing

scenarios(mc, *, bear_p=0.10, bull_p=0.90) -> list[Scenario]  # Bear/Base/Bull from the distribution

extract_segments(text, *, api_key=None, llm=None) -> dict  # segment skeleton from annual report
alignment_check(parsed) -> dict                            # Σ + residual ≈ reported total

Project structure

revenue-model-builder/
├── revenue_model/
│   ├── driver.py        # Driver — one factor (base/pen/share/price) + ABC grade
│   ├── segment.py       # Segment — revenue = base × pen × share × price
│   ├── model.py         # RevenueModel — residual + alignment validation
│   ├── monte_carlo.py   # revenue distribution + tornado sensitivity (pure stdlib)
│   ├── extractor.py     # annual-report text -> segment skeleton (LLM, pure stdlib)
│   ├── excel_builder.py # render to .xlsx (ABC colors, IF formulas, residual)
│   └── demo.py          # NovaTech fictional example
├── tests/               # 35 tests — formula, validation, residual, MC, tornado, extractor
├── docs/
│   └── design-principles.md
└── pyproject.toml

Roadmap

• Monte Carlo revenue distribution + sensitivity (tornado) analysis
• Segment skeleton extraction from annual-report text (LLM)
• Driver value estimation (C-grade, from industry data)
• Bear / Base / Bull scenarios (sliced from the Monte Carlo distribution)
• Multi-market data source adapters (A股 tushare / US yfinance / HK)
• Automated driver extraction from annual-report text
• Word memo builder (historical + forecast narrative)
• PyPI release

Who is this for

Sell-side research, PE/VC investment teams, equity analysts, and students of fundamental analysis who want a reusable, auditable revenue-modeling scaffold rather than rebuilding the same spreadsheet structure by hand.

License & disclaimer

MIT — see LICENSE. This is a research/education tool, not investment advice — full statement in DISCLAIMER.md.