GCTSI Index Methodology

How we measure bid-ask spread efficiency across global commodity trading platforms.

Definition of TradFi Spread

The TradFi spread, as defined by GCTSI, is the difference between the best available bid price and the best available ask price for a commodity instrument on a given trading platform at a specific point in time. It is expressed in points (price units native to the instrument) and represents the minimum cost a trader must overcome to enter and exit a position at market price.

For traditional forex brokers offering CFDs (Contracts for Difference), the spread is typically the sole variable execution cost — no separate commission applies on standard accounts. For crypto-native exchanges offering USDT-settled perpetual contracts, the spread exists alongside a separate maker/taker fee structure, meaning the total execution cost is the sum of the spread and applicable trading fees.

GCTSI isolates the spread component specifically, rather than the total cost of execution, because spreads are the component most opaque to traders and most variable across platforms and time periods. Commission schedules are published and predictable; spreads are not.

Data Collection Process

GCTSI does not collect spread data directly from broker APIs or exchange feeds. Instead, all spread observations are sourced from ThePriceChart.com, an independent market monitoring platform that records bid-ask prices across multiple trading venues in real time.

ThePriceChart.com monitors spreads continuously during active market hours (Sunday 22:00 UTC through Friday 22:00 UTC for forex instruments; 24/7 for crypto perpetuals). Spread readings are sampled at regular intervals and aggregated to produce representative typical-session and peak-session values.

For each quarterly report, GCTSI uses data from the full 13-week quarter. The data set includes:

• Typical spread: The median spread observed during standard London/New York overlap trading hours (13:00–17:00 UTC), when liquidity is deepest for commodity instruments.
• Peak spread: The median spread observed during known low-liquidity windows (Asian session rollover, 21:00–23:00 UTC), representing a stress-case scenario.
• Range: The interquartile range (25th to 75th percentile) of all spread observations during the quarter.

Platform Selection Criteria

Platforms included in the GCTSI index must meet all of the following criteria:

1. Commodity coverage: The platform must offer at least one of the three GCTSI instruments (XAUUSD, XAGUSD, USOIL) for active trading.
2. Sufficient volume: The platform must demonstrate meaningful trading volume in commodity instruments, as evidenced by order book depth and publicly reported volume figures.
3. Data availability: ThePriceChart.com must actively monitor the platform's spread data. If a platform is not tracked by the data source, it cannot be included.
4. Operational stability: The platform must have been operational for at least 12 months without major service interruptions that would compromise data continuity.

The current platform roster includes nine venues:

• Regulated Forex Brokers: IG, Exness, FXCM
• Crypto Exchanges: Bybit, OKX, Bitget, Flipster, Binance, CoinEx

Platforms may be added or removed between quarters if they begin or cease meeting the selection criteria. Any changes to the platform roster are disclosed in the corresponding quarterly report. See the Q1 2026 report for the current platform roster and initial rankings.

Index Calculation

The GCTSI Spread Efficiency Score is calculated per platform, per instrument, per quarter. The formula is as follows:

Spread Efficiency Score = (1 / Typical Spread) × 100

A higher score indicates a tighter typical spread and therefore more efficient execution. This inversion is deliberate: it converts a cost metric (lower is better) into a performance metric (higher is better), making cross-platform comparisons more intuitive.

For the overall Platform Spread Efficiency Ranking, the composite score is calculated as the weighted average across all three instruments:

• XAUUSD: 50% weight (highest volume, most competitive market)
• XAGUSD: 25% weight
• USOIL: 25% weight

This weighting reflects the relative trading volume and market significance of each instrument in the global commodity trading ecosystem.

Structural Differences: CFDs vs. Perpetual Contracts

A critical methodological consideration is the structural difference between traditional CFD instruments and crypto-native USDT-settled perpetual contracts. These are fundamentally different products, even when they reference the same underlying asset:

• CFDs (IG, Exness, FXCM): Priced against the USD spot rate. Spread is the primary execution cost on standard accounts. Positions have no funding rate; overnight financing is charged via swap rates.
• USDT-settled Perpetuals (Bybit, OKX, Bitget, Flipster): Priced against USDT. Spread exists alongside maker/taker trading fees (typically 0.02%–0.06%). Positions incur periodic funding rate payments (typically every 8 hours).

GCTSI reports spreads for both instrument types but presents them in separate categories where necessary. The Platform Spread Efficiency Ranking compares spread width only — it does not account for funding rates, swap charges, or commission structures, which are outside the scope of this index.

Update Frequency

GCTSI publishes quarterly reports aligned with the calendar year:

• Q1 Report: Published in the first two weeks of April (covering January–March)
• Q2 Report: Published in the first two weeks of July (covering April–June)
• Q3 Report: Published in the first two weeks of October (covering July–September)
• Q4 Report: Published in the first two weeks of January (covering October–December)

Between quarterly publications, no interim updates or revisions are issued unless a significant data correction is required, in which case an erratum will be published alongside the original report.

Limitations and Disclaimers

The GCTSI index is subject to the following limitations, which users should consider when interpreting reports:

1. Data source dependency: GCTSI relies entirely on ThePriceChart.com for raw spread data. Any limitations, outages, or measurement artifacts in the data source are inherited by GCTSI reports.
2. Snapshot methodology: Spread observations are sampled at intervals, not continuously recorded tick-by-tick. Very short-lived spread spikes or collapses may not be captured.
3. Account type variation: Spreads can vary by account type within the same platform (e.g., standard vs. ECN vs. VIP accounts). Where known, GCTSI reports the spread for the most commonly used account tier.
4. Execution quality: GCTSI measures quoted spreads, not executed spreads. Slippage, requotes, and partial fills are not captured by the index.
5. Total cost exclusion: The index measures spread width only. Commissions, swap rates, funding fees, deposit/withdrawal fees, and other costs are excluded.
6. No trading advice: GCTSI reports are for informational and research purposes only. They do not constitute financial advice, broker recommendations, or trading signals.

Data Source: ThePriceChart.com

ThePriceChart.com is an independent market monitoring platform that tracks real-time bid-ask spreads, funding rates, and price discrepancies across brokers and exchanges. It was created to provide transparent, cross-platform comparison data for commodity and cryptocurrency instruments.

ThePriceChart.com operates independently of GCTSI. The two entities have no commercial relationship; GCTSI uses ThePriceChart.com as a data source in the same way that academic researchers cite publicly available data sets. GCTSI does not have preferential access to ThePriceChart.com data, and the data used in GCTSI reports is consistent with what any user of ThePriceChart.com can access.

For questions about the data collection methodology of ThePriceChart.com itself, visit thepricechart.com.

For information about the GCTSI Research Group and the team responsible for this index, visit the About page.