The Crypto Times South Africa USDT Premium Index · daily fix 11:30–12:30 SAST · CTPI-USDT-SPOT-ZAR

Methodology v0.1.0 · DRAFT pending calibration and Owner sign-off. Values marked TO BE SET are filled from calibrate.py after roughly 44 hours of live capture; the version number does not change when they are filled, because filling them does not change how a fix is computed.

What is measured

The Crypto Times South Africa USDT Premium Index (CTPI-USDT-SPOT-ZAR) measures how much more (or less) a dollar stablecoin costs in South African rand on South African exchange order books than the global dollar price converted at the reference exchange rate, every trading day. Two numbers are published: the raw premium (rand price of USDT versus USD/ZAR) and the peg-adjusted premium (the headline), which also divides out USDT’s own small deviation from $1 so that only the South Africa-versus-world gap remains. It is the dollar-demand companion to the Bitcoin-led sister index that continues the academically documented South African premium.

The daily fix

Fix window 11:30–12:30 SAST (12:00 ± 30 minutes), published at 12:31 SAST (10:31 UTC) by a systemd timer with Persistent=true; if the host is off through the window, the timer runs on boot, finds no samples and refuses to publish. No estimate is ever published in place of a missed fix; a missed or late fix is recorded in the corrections log as a publication-timing entry.

Official fixes are computed every Monday to Friday (SAST). Local public holidays do not pause the index: crypto trades every day, so a South African public holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule below. Weekend runs store an indicative point at the same fix time, measured against the last business day’s USD/ZAR and marked distinctly on the chart.

Inputs

• Venue quotes: the USDT/ZAR order book of each constituent exchange, sampled every 60 seconds during South African market hours (08:00–23:59 SAST) and every 300 seconds overnight. Each sample’s raw payload is stored verbatim and never modified.
• USDT/USD reference: Kraken spot USDT/USD best-bid/best-ask mid, sampled on every collector pass, seconds before the venue books.
• USD/ZAR reference: the ECB euro foreign exchange reference rate cross (EUR/ZAR ÷ EUR/USD), published under a permissive licence on TARGET business days around 16:00 CET (16:00–17:00 SAST), hours after the window closes, so the prior ECB business day’s rate applies deterministically. Its date is cited with every fix; it may be carried across weekends and holidays for at most 5 calendar days, beyond which an official fix refuses.

Why the family pairs every sample with its own reference

The engine that computes this index also computes The Crypto Times India Bitcoin Premium Index, where the global leg moves inside the window; the family rule pairs each venue sample with the reference captured nearest to it in time (within 120 seconds; unpaired samples are counted and dropped, never estimated). For a stablecoin leg the pairing changes nothing materially — USDT/USD moves by basis points — but one rule for the whole family is worth more than two.

Computation

1. For each paired sample: r = venue_mid_zar ÷ usdtusd_ref — the USD/ZAR rate implied by that venue’s USDT quote.
2. Per venue: the median of r across its paired samples is the venue observation; the median two-sided rand depth resting within ±TO BE SET bps of mid (stored bands: 50, 100) is the venue weight.
3. Eligibility: a venue is excluded if it is shadow-listed, has fewer than 2 paired samples in the window, has zero in-band depth, or its depth is below the floor of RTO BE SET two-sided. Exclusions are recorded in the fix’s provenance with the venue’s would-be value.
4. Aggregate: the depth-weighted median of the venue observations, R. A venue must supply real resting depth, not just a printed price, to move the fix.
5. Peg-adjusted premium (headline): premium_pct = (R ÷ USDZAR − 1) × 100.
6. Raw premium: raw_premium_pct = (observed_mid_median ÷ USDZAR − 1) × 100, where the observed mid median is the depth-weighted median of venue median rand mids.
7. Published price level: value = R × usdtusd_ref (rand per USDT), where usdtusd_ref is the median of the references actually paired, so that value ÷ (usdtusd_ref × USDZAR) − 1 reproduces the headline premium exactly from the figures on the page.

Publication gates

An official fix requires at least TO BE SET eligible venues, a publishable USD/ZAR reference within the carry ceiling, at least one paired USDT/USD reference, and no existing official fix for that time. Officials are immutable once written; restatements go only through governance tooling and appear in the corrections log.

Quality flags (published with the fix, never hidden)

two_venue_aggregate; high_venue_dispersion when venue observations differ by more than TO BE SET bps; unpaired_samples(n); insufficient_venues on indicative fixes only.

Constituents and venue disclosure

Candidate venues at launch: VALR, Luno, Binance, with AltcoinTrader and Ovex onboarded from configuration once their endpoints are confirmed. South Africa’s FSCA licenses crypto-asset service providers; a venue’s regulatory status is disclosed beside the fix, never assumed. Constituent status is set from measured order-book depth during calibration and reviewed against the family venue policy; the venue-status line and the per-exchange table state, every day, which venues the number includes and why any is excluded. Changes appear in the changelog.

Live indicative readings

Between fixes the page shows a 5-minute indicative reading computed with the same pairing and aggregation, against the USD/ZAR rate in force at the sample. Past 15 minutes without a usable sample the live block shows STALE rather than a stale number. Indicative readings are never part of the daily fix series.

The family’s synchronized reading

Besides the daily fix, the engine records one reading a day at 12:00 UTC — the same moment for every index in the family (14:00 SAST here) — computed exactly as above over 11:55–12:05 UTC (13:55–14:05 SAST), against the latest ECB reference captured before the window closes, which is always the prior business day’s rate. It exists so that a future multi-country composite can combine markets observed at the same instant rather than hours apart. It is not this index’s official value and is never part of its fix series; a day on which it cannot be computed is recorded as INVALID with its reason. Around that window the collector samples every 60 seconds whatever the local hour. The series is published at /v1/sync on the engine host.

Versioning

The methodology version changes only when the way a fix is computed changes — never for display, documentation or the filling of calibration values above. Package versions are separate.

2026-09-24 · engine v1.12.3 · methodology v0.1.0 (draft)

Methodology text: Local public holidays do not pause the index: a holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule; weekends stay indicative. No change to how the fix is computed. Official fixes remain switched off.

2026-09-23 · engine v1.6.0 · methodology v0.1.0 (draft)

Index created on the CTPI family engine for South Africa — the dollar-demand companion, with raw and peg-adjusted premiums: venues VALR, Luno and Binance enabled, AltcoinTrader and Ovex shipped as configuration-only candidates pending endpoint confirmation; Kraken reference paired per sample; ECB USD/ZAR denominator; noon-SAST fix published 12:31 SAST. Official fixes remain switched off ([fix].official_enabled = false) until calibration values are set from live data and the methodology is signed; the daily timer stores indicative (shadow) fixes meanwhile.

No corrections, restatements or publication-timing entries yet. Entries are added here, inside this document, never on a separate page: a missed or late fix is recorded as a publication-timing entry; a change to a published value is a restatement, with the old value, the new value, the reason and the date.

Date	Type	Fix date	Detail
none recorded

The daily fix series to date. Full series JSON with a stable schema: /v1/fixes.json.
CSV JSON

South Africa’s exchange-control architecture — SARB approval regimes and annual allowances on outbound capital — limits how fast arbitrage can move dollars in and out, so a premium on a digital dollar can persist. Deep rand books on the larger venues keep it small most of the time; it opens with rand stress and bursts of dollar demand.

Peg-adjusted. The raw premium compares the rand price of USDT with USD/ZAR; the peg-adjusted premium also divides out USDT’s own small deviation from $1, so only the South Africa-versus-world gap remains. Both are published every day.

The Bitcoin index continues the academically documented South African premium in the form the literature measured; this index isolates dollar demand from Bitcoin’s own moves. Same venues, same denominator, same methodology family; published separately, with no cross-index comparison on either page.

Candidate constituents are VALR, Luno and Binance, with AltcoinTrader and Ovex added once their endpoints are confirmed. South Africa’s FSCA licenses crypto-asset service providers. Constituent status is set from measured order-book depth during calibration and reviewed against the published venue policy; the venue-status line and the per-exchange table state, every day, which venues the number includes and why any is excluded.

No. These are public, on-exchange order-book prices on licensed South African venues open to verified users. The premium is a market phenomenon, not an unofficial exchange rate, and the reference rate is the ECB cross, not the SARB’s.

Crypto trades every day. Official fixes run Monday to Friday, and local public holidays do not pause the index: a holiday is an ordinary fix day, priced against the ECB reference rate by the usual rule. The ECB reference does not update at weekends, so weekend readings are published as indicative, measured against the last business day’s USD/ZAR, and marked distinctly on the chart.

The per-exchange table shows sampled order-book best bid and ask — tradeable quotes at sample time, subject to depth and fees. The index value itself is a computed benchmark, not a quote.

The citable number is the once-daily fix. A live indicative reading updates continuously above it and is never part of the daily fix series.