Q1 2026 C100 Rebalance — What Changed and Why
New entrants, removals, and weight shifts driven by carbon-side capacity additions and transition-score upgrades.
Abstract
Routine quarterly rebalance with above-average turnover. Six additions, five deletions, and twenty material weight changes. Carbon-side cohort gained 220bps of aggregate weight; market-side cohort lost 180bps.
Key Findings
- 01Index turnover: 11.4% by weight, above the 7-9% trailing four-quarter average.
- 02Six additions — three in DAC/removal, two in MRV, one in carbon insurance.
- 03Five deletions — two on Greenwash upgrade, two on Financial Strength downgrade, one on M&A.
- 04Sector caps: technology and industrials hit the 25% cap for the second consecutive quarter.
1. Headline changes
The rebalance reflects a structural tilt we have flagged for two quarters: capacity additions in removal technology are finally large enough to move the index. DAC and biochar names collectively added 180bps of weight.
2. Why the turnover spiked
Two of the five deletions were Greenwash-driven, not score-driven, which is unusual. The methodology requires immediate removal on a Medium-to-High upgrade where verified drift exceeds 25% — a rule that triggered for the first time this quarter.
3. What didn't change
The top ten constituents by weight are unchanged. The cap structure (4% single name, 25% sector) continues to absorb most of the score-driven moves before they reach the index weight.
Q1 2026 sector weight deltas
| Sector | Q4 2025 | Q1 2026 | Δ |
|---|---|---|---|
| Removal Tech | 8.2% | 10.0% | +180 bps |
| MRV / Registries | 6.5% | 7.4% | +90 bps |
| Carbon Insurance | 2.1% | 2.6% | +50 bps |
| Upstream O&G | 11.4% | 10.5% | -90 bps |
| Airlines | 5.0% | 4.2% | -80 bps |
| Fast Fashion | 3.1% | 2.6% | -50 bps |
Implications
- →Expect higher tracking error vs. broad equity benchmarks this quarter due to the removal-tech overweight.
- →Allocators replicating C100 should plan for ~60bps of one-way transaction cost on rebalance day.
- →Next rebalance consultation opens 2026-06-01.
Methodology
- • Selection: top 100 by CIP score within the eligible universe, subject to liquidity floor.
- • Weighting: CIP^1.3 with 4% single-name cap and 25% sector cap.
- • Implementation: single-day rebalance, VWAP-style.
Sources & References
- C100 Rules v0.1
- Q1 2026 Rebalance Dataset (CSV)
This research note is published by the Carbon Index Protocol research desk for informational purposes only. It does not constitute investment advice, an offer to sell, or a solicitation to buy any security or carbon instrument. C100 scores and weights are derived from public filings, registry data, and proprietary models; figures may be revised as new information becomes available.