Banks widen spreads when markets are closed, volatile, or simply when it’s Friday. We publish one margin and hold to it — mid-market plus 25 basis points, with a disclosed weekend buffer and nothing hidden. Keeping that predictable through weekends and rate shocks is an engineering problem, not a pricing one.
What “mid-market” means
There is no single official exchange rate. There are venues — EBS, LMAX, Currenex, a dozen others — each with its own order book. “Mid-market” is a constructed number: the midpoint between the best bid and best ask across the venues you trust, weighted by depth. We compute our mid from five institutional venues, refreshed every 50ms for major pairs, trimming outliers before the midpoint is taken.
The rate stream
Internally, rates are a stream, not a table. Every consumer — the quote API, the converter widget, the payout engine, the ledger’s revaluation job — subscribes to the same feed, so there is exactly one answer to “what was EUR/USD at 09:14:07.250” anywhere in the system.
{
"pair": "EURUSD",
"mid": 1.08423,
"venues": 5,
"spread_bps": 0.4,
"staleness_ms": 38,
"regime": "open"
}30-second quotes
An indicative rate is a screenshot; a quote is a contract. When you request a quote, we freeze the rate for 30 seconds and will fill at that rate even if the market moves against us inside the window. The 30-second risk is hedged statistically across the whole book rather than per-trade: at our volume, the moves cancel.
The weekend problem
FX markets close Friday 22:00 UTC and reopen Sunday 21:00 UTC. Your marketplace does not. We price weekend conversions from Friday’s close plus a regime-dependent buffer that we publish — currently 15 bps for majors. So a weekend EUR→USD costs mid + 40 instead of mid + 25, the number is on the pricing page, and Monday morning it snaps back automatically.
Never the worst price
The goal is the one that compounds: never being the worst price you got that month, and never making you check. A fixed, published margin over a defensible mid turns FX from a thing finance teams audit into a constant they configure. The best FX rate is the one you stop thinking about.