Estimate portfolio diversification benefit

Measure coherent portfolio diversification by comparing joint-scenario CVaR with standalone CVaRs and reconciling Euler tail-risk contributions, stress loss, and concentration gates.

What it's for

Quantifies whether a startup, product, or engineering investment portfolio is truly diversified in bad states—not merely spread across many line items—and shows which exposures dominate the tail.

What you give it

Inputs split into evidence read from your connected systems, calibration your team owns, and numerical controls that affect precision but never the result's meaning.

Field Type Role Required
holdings array of objects (3 fields) ≥ 2 items Evidence Yes
max_detail_rows integer ≥ 1, ≤ 500 Numerical control Optional
maximum_portfolio_cvar_loss number ≥ 0 Your calibration Optional
maximum_single_risk_contribution_share number ≥ 0, ≤ 1 Your calibration Optional
minimum_downside_diversification_benefit number ≥ 0 Your calibration Optional
scenarios array of objects (3 fields) ≥ 2 items Evidence Yes
tail_probability number ≥ 0.001, ≤ 0.5 Your calibration Optional

Each holdings record

Field Type Required
capital_at_risk number (> 0) Yes
id string (non-empty) Yes
return_scenarios array of number (≥ 2 items) Yes
Example input
{
  "holdings": [
    {
      "capital_at_risk": 100,
      "id": "growth-products",
      "return_scenarios": [
        0.3,
        0.1,
        -0.2,
        -0.4
      ]
    },
    {
      "capital_at_risk": 100,
      "id": "infrastructure-savings",
      "return_scenarios": [
        -0.1,
        0.05,
        0.2,
        0.35
      ]
    }
  ],
  "maximum_portfolio_cvar_loss": 10,
  "maximum_single_risk_contribution_share": 1,
  "minimum_downside_diversification_benefit": 10,
  "scenarios": [
    {
      "id": "expansion",
      "probability": 0.25
    },
    {
      "id": "base",
      "probability": 0.25
    },
    {
      "id": "slowdown",
      "probability": 0.25
    },
    {
      "id": "severe-downturn",
      "is_stress": true,
      "probability": 0.25
    }

Truncated for display — the full payload is 47 lines.

What you get back

This is the actual output of running the example above — computed by the same function the platform calls, not an illustration.

Example output
{
  "assumptions": [
    "Every holding return uses the same coherent joint scenario column and horizon; probabilities, capital, currency, valuation, liquidity, follow-on obligations, and loss sign are comparable, and independently sorted marginal scenarios are prohibited because they manufacture diversification.",
    "Diversification benefit compares portfolio CVaR with the sum of standalone CVaRs under the same probability law; Euler tail contributions reconcile to portfolio CVaR and may be negative for genuine hedges, but neither contribution nor leave-one-out change is causal attribution.",
    "Historical or simulated scenarios must include common shocks, tail dependence, concentration, nonlinear payoffs, dilution, and missing valuations that matter; a high ordinary diversification ratio cannot override weak stress coverage or an explicit risk-concentration gate.",
    "Holdings are aggregate companies, projects, products, services, or asset exposures, never named employees; this result is not investment advice, a valuation, a capital-allocation order, or authorization to buy, sell, fund, or terminate anything."
  ],
  "configuration": {
    "maximum_portfolio_cvar_loss": 10,
    "maximum_single_risk_contribution_share": 1,
    "minimum_downside_diversification_benefit": 10,
    "scenario_alignment_preserved": true,
    "tail_probability": 0.25
  },
  "decision": "portfolio_diversification_clears_governed_risk_gates",
  "holding_diagnostics": [
    {
      "capital_at_risk": 100,
      "expected_pnl": -5,
      "hedges_portfolio_tail": false,
      "holding_id": "growth-products",
      "leave_one_out_portfolio_cvar_change": -5,
      "portfolio_tail_risk_contribution": 40,
      "positive_tail_risk_contribution_share": 1,
      "standalone_cvar_loss": 40,
      "standalone_volatility": 26.9258
    },
    {
      "capital_at_risk": 100,
      "expected_pnl": 12.5,
      "hedges_portfolio_tail": true,
      "holding_id": "infrastructure-savings",
      "leave_one_out_portfolio_cvar_change": -35,
      "portfolio_tail_risk_contribution": -35,
      "positive_tail_risk_contribution_share": 0,
      "standalone_cvar_loss": 10,
      "standalone_volatility": 16.7705
    }
  ],
  "method": "coherent_scenario_cvar_diversification_benefit_v1",
  "scenario_diagnostics": [
    {
      "is_stress": true,
      "portfolio_loss": 5,

Truncated for display — the full payload is 98 lines.

How it works

Constrained optimization — Pick the best feasible option under real limits — budget, headcount, dependencies, capacity — rather than ranking a list and hoping it fits.

  1. 1 Freeze holdings, capital at risk, valuation horizon, and one aligned joint scenario matrix with common probabilities and stress labels; reject independently sorted or marginal-only forecasts that destroy dependence.
  2. 2 Compute holding and portfolio P&L, fractional-tail CVaR, coherent and downside diversification benefit, volatility diversification, and exact Euler contributions using the portfolio's own tail weights.
  3. 3 Reconcile contributions to portfolio CVaR, identify true tail hedges and leave-one-out effects, and recommend only when downside benefit, absolute portfolio loss, and positive risk-contribution concentration all clear governed limits.

Before you trust it

Every tool in the catalog ships with the conditions under which its answer is meaningful — and the conditions under which it should abstain instead of guessing.

Assumptions & guardrails

  • Objectives use commensurable locally governed value units, constraints reflect real feasibility, and uncertainty covers plausible adverse inputs.
  • Scenario columns are genuinely joint across holdings and include common shocks, tail dependence, nonlinear payoffs, dilution, liquidity and follow-on exposure; capital and return definitions are comparable and probabilities represent the governed prospective distribution.
  • The recommendation is optimal only for its stated objective, feasible set, evidence, and solver guarantee; it is not a universal management optimum.
  • Diversification and Euler contribution are scenario-conditional risk measurements, not causal performance attribution or investment advice; holdings must be aggregate companies, projects, products or services, never named employees.

Minimum evidence

  • holdings: at least 2 rows/items
  • scenarios: at least 2 rows/items

How to validate it

Backtest the chosen action against simple feasible baselines on held-out scenarios, sweep costs/constraints/risk tolerance, and require constraint feasibility under adverse inputs.

Calibrating it to your org

Same for everyone

The mathematical kernel, validation rules, method version, and JSON output semantics are organization-independent; no tenant-trained coefficients or company benchmark is embedded in the function.

Specific to you

  • joint portfolio scenario matrix retaining common shocks, tail dependence, nonlinear payoffs, valuation uncertainty, liquidity, dilution, and follow-on commitments in one horizon and currency basis
  • portfolio and exposure perimeter, valuation vintage, scenario probability law, stress definitions, tail probability, minimum downside diversification benefit, maximum portfolio CVaR, contribution concentration limit, and review cadence

Calibration workflow

  1. 1 Define the management decision, target outcome, aggregate unit, privacy boundary, cadence, and prediction/intervention horizon for this organization.
  2. 2 Build a tenant-scoped historical cohort using only information available before each prediction or decision; preserve zero periods, censoring, assignment probabilities, and unresolved outcomes when the method requires them.
  3. 3 Estimate statistical parameters on training history, but obtain costs, utilities, risk tolerance, practical-effect thresholds, capacity, and policy constraints from accountable decision owners.
  4. 4 Validate on later time windows or held-out aggregate units at the deployment grain, against a simple baseline and the function-specific validation strategy.
  5. 5 Deploy only if the returned decision clears evidence, overlap, calibration, robustness, and guardrail checks; warning, unsupported, schema-gap, and fallback decisions are abstentions.
  6. 6 Monitor realized outcomes, data drift, coverage, and decision regret; recalibrate at a governed cadence or after a detected regime/definition change, never merely because a stakeholder dislikes the result.

Call it from your AI

You don't wire up 388 tools in your MCP client. The GitRevio MCP server exposes 18 tools, three of which let an agent search the catalog, read a tool's schema, and run it — so the assistant finds this one on its own.

gitrevio_capabilities_search
  { "q": "measure coherent portfolio diversification by comparing" }
  → finds "estimate_portfolio_diversification_benefit"

gitrevio_capability_describe
  { "capability_id": "estimate_portfolio_diversification_benefit" }
  → returns the input schema and agent guidance shown on this page

gitrevio_capability_run
  { "capability_id": "estimate_portfolio_diversification_benefit", "arguments": { ... } }
  → returns the result shown above

Works in Claude Desktop, Claude Code, Cursor, Cline, Continue.dev, Goose and Aider. See the MCP server.

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