I've been thinking about a distributed market owned by a mutually anonymous, closed set of shareholders, and managed analogously to a corporation in real life, with ownership both tracked
and enforced cryptographically. This operates similarly to existing centralized markets for physical goods, sold by mail between untrusting sellers and buyers. So---
- Important decisions (like whether a new seller may post listings, or when to release escrow if the buyer and seller can't agree) are made by shareholder vote.
- In some cases, the shareholders vote to temporarily delegate limited authority to a single person, like a customer service representative. That person may or may not be a shareholder.
- Commission on orders is paid to shareholders in proportion to their stake.
This structure lets the market's initial owners sell it---in whole or in part---to one or more anonymous buyers, with no need for trust in either direction. Authority to manage the market always derives from the most recent shareholder vote. This is different from most proposed distributed markets---those distribute hosting of the listing and order database, and allow any participant to serve as a paid escrow agent, but that escrow agent is always a single person or real-life entity. This is one step beyond the usual proposals to track ownership of securities in the blockchain---we do that, and then the buyers and sellers run a computer program to interpret that ledger, checking signatures from and making payments to the owners without human intervention.
The market is hosted on a small number of nodes that just store and flood-route messages, probably (though not necessarily) operated by the owners, as hidden services. Buyers and sellers run a local client that receives and sends messages. From those messages, and from a hard-coded root owner's public key, the client can compute a "cap table" of the market's ownership. From that cap table, it can determine whether subsequent messages are signed by the required majority of shareholders, and interpret messages with valid signatures to show listings and place orders.
Payment is made by Bitcoin, with the usual 2/3 multisig. Buyers and sellers are responsible for paying commission to the owners. Nothing stops them from cheating---but the seller and buyer must collude to do that, and the owners will notice immediately and ban both users, destroying the reputation they've built with their transaction history. The identity of an owner, seller, or buyer is a cryptographic key pair, and most details of how messages are signed or encrypted are obvious. Bitcoin is used for timestamps, both just to prove which message came latest (like a message to approve or ban a seller---there's no benefit to forging an earlier message, since the later one would still supersede it) and to order messages in an append-only log (like a message to transfer ownership of shares---an earlier forged message could make the shares unavailable to transfer later).
This structure is interesting to me---joint-stock companies have shown an extraordinary ability to grow and survive in real life, so it seems plausible that their crypto-security equivalent would do the same, with no one person capable of shutting it down. The concept is described more in:
Is anyone aware of similar work already underway? And does the structure described in those links seem practical? The owners' incentives to behave honestly are messier than for a currency, and often depend, for example, on the market's price/earnings ratio, or other quantities that are hard to predict. So the numbers are debatable---but is the basic form of the arguments correct?