Premium NatGas Index Methodology
This document is published on the same footing as our FERC-equivalent compliance pages, per Standard 4 audit obligations. It is the authoritative reference for how every published CMP-NG™ cell is derived. Every index carrying the CertiMark Verified seal is held to this same bar.
What the index measures
The CertiMark Premium NatGas Index (CMP-NG™) reports the price premium — in USD per MMBtu — paid on pipeline natural gas certified under MiQ, Project Canary, or Equitable Origin, above the host-hub commodity index for the same delivery window. Trades are weekly VWAP-averaged and dimensioned by certifier, grade, and contract type.
What counts as a submission
- Arms-length, non-affiliate trades between a qualifying Panelist and a third-party counterparty
- Delivery of certified gas that meets the claimed standard and grade for the entire delivery window
- Fixed-price or basis-fixed premium over an identified host hub index
- Trade date within T+7 days of submission
- Certification in-period (grade not expired) at trade date
The CertiMark 5 / 40 / 10 rule
Every published cell must pass three automated tests enforced by a Soda Core SQL-pushdown scan before publication. If any test fails for any cell, that cell publishes as "insufficient data" — no partial workaround is permitted. This is the same rule applied identically across every index under the CertiMark seal.
| Rule | Threshold | Implementation |
|---|---|---|
| k-anonymity | ≥ 5 distinct Participants per cell | COUNT(DISTINCT user_id) in Soda Core |
| concentration cap | No Participant > 40% of cell volume | SUM(volume) grouped by user_id; HAVING > 40% of total |
| transaction floor | ≥ 10 accepted transactions per cell | HAVING COUNT(*) < 10 failure check |
Raw identity is never persisted
Before any INSERT reaches the staging table, the raw counterparty name is transformed into a 64-character SHA256 hash using the currently active CertiMark governance salt. The salt rotates per publication period. Historical scans remain reproducible because each submission stores the salt that was active when it was recorded.
Volume-weighted average premium
For each accepted submission passing the CertiMark 5/40/10 gate:
VWAP_premium = SUM(price_premium × volume) / SUM(volume)
Published alongside VWAP: 25th / 75th percentile interquartile range, accepted transaction count, and accepted volume. Individual trades are never published.
Standard 5 correction log
Any published value may be corrected if an underlying submission is later excluded via admin review. Every correction is logged with before/after values, the trigger reason, and the user responsible. The correction log is public and applies to every index under the CertiMark seal.
Procompetitive structure
Following the DOJ's 2023 withdrawal of formal price-reporting safety zones, every CertiMark-Verified index defends its Panelist model as a procompetitive structure rather than a bright-line safe harbor. The pillars of that defense are:
- Independence — neutral third-party PRA, not an industry association
- Rigorous k-anonymity via the 5/40/10 rule
- Weekly (not real-time) publication so data is too stale for live coordination
- Solving information asymmetry in a nascent market — a recognized procompetitive benefit
- Non-discretionary, code-enforced rule application with full audit trail