というNBER論文をブルナーメイヤーらが上げているungated版へのリンクがある著者の一人のページ)。原題は「Strategic Money and Credit Ledgers」で、著者はMarkus K. Brunnermeier(プリンストン大)、Jonathan Payne(同)。

This paper studies strategic decision making by a private currency ledger operator, which faces competition from public money and/or other ledgers. A monopoly ledger operator can incentivize contract enforcement across the financial sector by threatening exclusion, but it can also impose markups through its pricing power. Currency competition limits rent extraction, but also makes coordinated contract enforcement more fragile. The emergent market structure bundles the provision of ledger and platform trading technologies. Regulation to ensure platform cooperation on contract enforcement and competition on markup setting is effective so long as agents can easily switch between platforms.


We have seen increasing competition in the provision of currencies and ledgers for settling transactions and contracts. BigTech consumer platforms have started to offer their own tokens and/or payment services (e.g. Alibaba, Meta, Amazon). Large supply chains have started to move payments and contracting onto shared ledgers (e.g. Corning, Emerson, Hayward). The “DeFi” community has provided decentralized ledgers to replicate traditional financial services (e.g. Ethereum, Solana). These changes make it important to understand what happens to the macroeconomy when a large, strategic, private institution provides the currency ledger. Can the ledger controller improve contract enforcement? Can they extract additional rents? How does a private token compete with public money? What is the likely market structure? How should regulators respond? To address these questions, we build a dynamic general equilibrium production model with private control of settlement assets and ledgers.
我々は、取引決済と契約締結のための通貨と台帳を提供する競争が激化するのを目にしてきた。巨大ITの消費者プラットフォームは、独自のトークンおよび/もしくは支払いサービスの提供を開始した(例:アリババ、メタ、アマゾン)。大手のサプライチェーンは、支払いと契約を共有台帳に移行し始めた(例:コーニング、エマソン、ヘイワード*1)。「分散型金融」界隈は、従来の金融サービスを複製するために分散化された台帳を提供してきた(例:イーサリアム、ソラナ)。こうした変化は、大手の戦略的な民間機関が通貨台帳を提供する時にマクロ経済に何が起きるかを理解することの重要性を高める。台帳管理者は契約執行を改善し得るのか? 彼らは追加的なレントを引き出すのか? 民間のトークンは公的な貨幣とどのように競合するのか? 市場構造はどのようなものになる可能性が高いのか? 規制当局はどのように対応すべきか? これらの問題に取り組むため我々は、民間が決済資産と台帳を管理する動学的一般均衡生産モデルを構築した。


In this paper, we model the strategic decision making of a private controller of the currency ledger used for settling transactions and writing contracts. We find that in an unregulated economy “BigTech” platforms are likely to provide “FinTech” services. This brings both benefits and costs. Tech platforms can expand uncollateralized credit across a supply chain by exploiting their control of the payment system to better coordinate the financial system to enforce contracts. However, Tech platforms will also use their control of the ledger to increase their market power and charge high markups. We see these issues playing out in China where tech platforms Alibaba and WeChat have created a well-functioning payment system with very limited competition.
Ultimately, our model suggests that currency ledgers may need to be regulated like other natural monopolies. This could include restrictions on when ledgers can cooperate on contract enforcement and compete on markups. It could also include a competing public option in the form a programmable Central Bank Digital Currency (CBDC) ledger. We consider further modeling of the government’s regulatory options as important future work.

*1:cf. 関連記事