The Duke of Orléans enclosed his garden in shops and discovered that royal ground sat outside police jurisdiction. Booksellers, gaming houses and unlicensed agioteurs moved into the arcades, and for forty years France's real price of government debt was set under this colonnade — four decades before the Bourse was given a building. Palais-Royal Exchange rebuilds that arrangement honestly: three venues with different economics, one router that proves which one deserved your order.
Figures on this page are illustrative and deterministic — a reference market, not live data.
Victor Louis built three galleries around the garden and rented every ground-floor bay to whoever paid. We kept the arrangement. Each venue below is a distinct market structure with its own failure mode — a book that runs thin, a pool that punishes size, a desk that simply stops. None of them wins every order, which is the entire reason the router exists.
Brokers without a licence — la coulisse — kept quoting rentes in the open air, and on several instruments they beat the official sixty on price. Their advantage was not secrecy but the opposite: everyone standing on the Perron could see the same size at the same moment. Every resting order here is readable before you trade against it.
The router fills your order one increment at a time, always into whichever venue offers the cheapest next unit. When marginal prices equalise, the split is cost-minimal — that is the whole algorithm, and it is why the answer changes with size rather than with marketing. Below every result is the counterfactual: what the same order would have cost sent to one venue alone.
The official brokers of the Ancien Régime held sixty hereditary seats and charged what the seat was worth. The coulisse undercut them because its pricing was published and identical for everyone who showed up. Fees here are stated in basis points, not derived from your order flow.
| Venue | Structure | Taker | Maker | Fill limit | Fails by |
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Worth knowing because the ending repeats. An open venue attracts real price discovery, real price discovery attracts scale, and scale invites an authority to enclose it. The Palais-Royal was free until it was replaced by a building with a door.
Each clause below is falsifiable from public data. That is the only kind of promise worth publishing — if you cannot check it, it is decoration.
It asked whether you could pay the rent and quote a price. Custody stays in your account until a fill is signed, the book stays readable, and every route ships with the receipt that proves it.