来源：复旦金融评论

■作者：Franklin Allen美国金融协会前主席、伦敦帝国理工学院商学院讲席教授、复旦大学国际金融学院国际咨询委员会联席主席

■公众号：复旦金融评论

货币创新的效应取决于该创新源自公共部门还是私人部门。

Franklin Allen

美国金融协会前主席

伦敦帝国理工学院商学院讲席教授

复旦大学国际金融学院国际咨询委员会联席主席

全球货币版图正被三股力量重塑：稳定币、央行数字货币（CBDC）和金融科技公司。每一股力量都有自己的拥趸、自己的叙事和自己的政策主张。然而，这些力量并非各行其道——它们彼此交织、时而互推、时而对冲——其互动的走向将决定未来数十年的金融架构。

本文的核心论点是：当前讨论的框架存在根本性的偏误。真正的问题不是稳定币和CBDC“谁能胜出”，也不是数字货币是否会“挤占”银行，而是：当新的类货币资产进入一个银行已不再占主导地位的金融体系时，系统如何调整？在与Ansgar Walther的最新理论研究（Allen and Walther, 2025）中，笔者将论证：货币创新的效应取决于该创新源自公共部门还是私人部门——而这一区分在政策讨论中几乎被忽略了。

稳定币：名中带“稳”，实则未必？

比特币最初被设计为支付手段，但其价格的剧烈波动使其难以胜任这一角色。稳定币——如曾提议的Libra和已落地的Tether——通过锚定法币来克服这一缺陷。然而，“稳定币”这一名称本身就掩盖了一个根本性张力。

2022年5月Terra-Luna生态中UST的崩盘并非偶发事件，而是利率环境的结构性产物。当利率处于零或接近零时，稳定币发行方为覆盖成本并向持有者提供一定回报，不得不投资于能产生正收益的风险资产，于是自身也变得具有风险。换言之，稳定币的“稳定”是有条件的——它取决于利率环境。这一点，当前的监管框架尚未充分消化。

如今，全球两大主流稳定币恰好呈现了流动性与合规之间的取舍。Tether（USDT）市值约1900亿美元，在交易所流动性和全球覆盖面上无可比拟，但其储备构成包含现金、美国短期国债、公司债、比特币和黄金，且缺乏完整审计透明度。Circle（USDC）市值约770亿美元，储备由现金和短期美国国债构成，在美国完全持牌并符合欧盟MiCA监管。市场实质上已分化为两极：一端优化交易便利性，另一端优化监管信任。

大西洋两岸的监管推进迅速。欧盟《加密资产市场监管法案》（MiCA）于2024年12月生效，为稳定币建立了法律框架。美国《GENIUS稳定币法案》于2025年7月签署。两者共享一个关键条款：禁止向稳定币持有者支付利息。

这一禁令旨在防止稳定币演变为影子银行存款。在与Angela Gallo的早期合作研究中，我们认为，它同时制造了一个潜在的竞争动态，该动态可能被证明具有破坏性。如果任何一个司法管辖区率先允许向稳定币支付利息，资金将迅速涌入该辖区的发行方；为争夺存款而展开的竞争可能迫使发行方再度投资于高风险资产——正是当初瓦解UST的机制。此处的类比是美国20世纪60年代的Regulation Q：银行存款利率上限迫使资本流向伦敦不受监管的欧洲美元市场，其后果用了许多年才完全显现。同样的监管套利逻辑今天依然适用，只是载体变成了稳定币。

央行数字货币：主权者的回应

如果说稳定币是市场试图改进法币支付效率的产物，那么CBDC则是主权者试图自我革新的尝试。探索的速度令人瞩目：截至2026年5月，已有146个国家和货币联盟在研究某种形式的CBDC，而2022年5月仅有87个。77个国家已进入探索高级阶段（开发、试点或推出），全球共有41个试点项目正在运行。

然而数字可能产生误导。仅有三个国家——巴哈马、牙买加和尼日利亚——全面推出了CBDC，且都面临采用率低迷和持续的技术挑战。这说明，CBDC的实际推广不仅取决于技术上线，还取决于用户接受度、使用场景和制度信任等因素。

不过，两个最重要的CBDC项目并不在小岛经济体，而在全球主要货币区。中国数字人民币（e-CNY）仍是全球最大规模的CBDC试点：截至2025年12月，已处理超过34亿笔零售交易，交易额约16.7万亿元人民币（约合2.3万亿美元）。与此同时，由中国人民银行授权的人民币跨境支付系统（CIPS）的一些交易已通过自主渠道完成结算。以SWIFT口径衡量的数据难以全面反映e-CNY的实际使用规模，因为它们遗漏了快速增长的双边e-CNY结算——这些结算未依托传统基础设施，而是经由独立数字渠道完成。

欧洲央行正在推进数字欧元，将其定位为“全球欧元时刻”，旨在强化欧元的国际角色并保护欧洲的支付主权。e-CNY与数字欧元虽表述不同，但共享一个底层逻辑：推动多极化货币秩序。这不仅仅是技术项目，也在影响着国际货币格局。

G20国家中除美国外均在探索CBDC，其中18个已进入高级阶段、14个处于试点阶段。美国的立场——仅由纽约联储通过Project Agorá开展批发型跨境研究——与其在稳定币领域激进的立法行动形成鲜明对比。这种不对称也与美元在现有国际货币体系中的地位有关。

理论告诉我们什么：公共创新 vs. 私人创新

上述讨论引出了一个稳定币拥趸和CBDC支持者都未充分回答的问题：当新的类货币资产进入一个银行已不再占主导地位的金融架构时，会产生什么系统性效应？

在最新研究中（Allen and Walther, 2025），我们构建了一个一般均衡模型来回答这一问题。模型中存在异质性金融中介——银行与非银行——它们竞争向家庭提供货币服务。在最简化的模型设定下，银行享有政府担保，非银行则不享有。家庭从货币服务中获得效用，而货币服务由银行存款、非银行债券和央行基础货币的直接持有的组合所产生。关键的内生变量包括类货币资产的便利性收益、银行与非银行的市场份额，以及各类中介的杠杆选择。

我们的核心发现是：货币创新的效应取决于该创新是公共的还是私人的。

公共货币创新——如引入CBDC以增加家庭对央行货币的直接持有——产生清晰的结果。在温和条件下，CBDC会降低整个金融体系的杠杆率，将投资从银行向非银行再配置，并降低金融不稳定性（以银行倒闭概率和政府担保的预期财政成本衡量）。福利效应明确为正。直觉很简单：当央行提供一种有竞争力的类货币资产时，银行存款的便利性收益下降，银行吸收的存款减少，杠杆率降低，其系统重要性随之下降。

这一结果挑战了CBDC将“挤占”金融中介的普遍担忧。在我们的模型中，银行的贷款确实下降了，但非银行的贷款同步扩张。更重要的是，银行杠杆率的内生下降意味着整个金融体系变得更加稳定，而非更不稳定。“挤占”叙事在狭义会计意义上并非错误，但它遗漏了一般均衡中杠杆调整这一关键维度。

私人货币创新——如稳定币的引入或金融科技支付平台的出现——则呈现不同的图景。其效应不确定，取决于银行和非银行的初始市场份额。我们识别出两个对立机制。一是债务估值效应：创新提高了非银行债务的便利性收益，促使非银行扩张。二是再配置效应：随着非银行对投资的支付意愿上升，资本价格上涨，投资从银行向非银行迁移。由于银行是货币服务的主要供给者，这种迁移导致整体货币供给收缩。

哪个效应占主导取决于起点。当非银行已拥有较大市场份额——如美国，非银行贷款机构供应了约60%的总信贷——债务估值效应倾向于主导，结果类似于公共创新：货币服务扩张、杠杆降低、稳定性改善。但当非银行初始市场份额较小——如在银行主导型经济体中，或当新的金融科技公司刚开始提供支付服务时——再配置效应初期占主导。货币服务的价格呈驼峰形上升，银行承担更多杠杆，金融稳定性先恶化，随后随着非银行站稳脚跟才逐步改善。

据我们所知，这种公共创新与私人创新之间的不对称尚未被政策文献所识别。它意味着：将稳定币或金融科技支付引入银行主导型金融体系——这一类别包括大部分欧洲大陆经济体和许多新兴市场——初期可能是不稳定的，即使长期效应是良性的。政策制定者应审慎考虑这一过渡性风险。

金融科技公司：被忽视的第三种力量

截至目前，讨论围绕稳定币和CBDC展开，但数字货币争论中还有一个常被忽视的行动者类别：金融科技公司。英国的Revolut数字银行是一个典型例证。

Revolut完全数字化运营，没有任何实体网点。它提供接近批发价的外汇牌价、远高于传统银行的储蓄利率，以及零手续费、数秒到账的跨境美元转账。在实践中，它在用户最关心的维度——速度、成本和可及性——上优于稳定币和传统银行。

这不是特例，而是新金融架构的结构性特征。金融科技公司兼具银行牌照的监管优势（包括存款保险）与数字运营的成本优势。需要指出的是，这一特征使金融科技公司在某种程度上不同于我们模型所定义的“非银行中介”——后者不享有同等强度的政府担保或存款保险。金融科技公司更接近于一种“混合型中介”：在运营效率上接近非银行，但在监管保障上接近银行。其含义是：持牌金融科技公司凭借低成本、高储蓄回报、便捷的产品触达和存款保险的组合，或将成为金融体系中的主导者，其对杠杆和金融稳定的影响可能与模型对纯粹非银行中介的预测存在显著差异。它们不应被忽视。

重新审视争论

上述三股力量——稳定币、CBDC和金融科技公司——经常在不同的政策孤岛中被分析：稳定币被视为加密资产问题，CBDC被视为央行问题，金融科技公司被视为竞争问题。这种碎片化遮蔽了更大的图景。

我们从理论研究中得到的核心教训是：货币创新的效应不能孤立评估。真正重要的是创新被引入的金融架构——尤其是银行和非银行的市场份额与杠杆选择。一个在美国这样的非银行比重较高的体系中改善稳定性的CBDC，在一些欧洲经济体这样银行比重较高的体系中可能产生不同效果。一个在非银行已站稳脚跟时无害的稳定币，在非银行尚未建立时可能引发不稳定。而改善了用户体验的金融科技支付平台，在过渡期可能触发令审慎监管者忧虑的杠杆调整。

政策启示直接由此得出。第一，稳定币监管框架必须预判利息禁令所创造的竞争动态。Regulation Q的先例表明，各辖区监管规则的差异将产生套利资金流，而利息禁令的最终放松——如果发生——应当是协调行动而非单边行为。第二，CBDC的设计必须考虑金融架构。在银行主导型体系中，零售型CBDC与批发型CBDC对金融稳定的影响各不相同。我们模型所揭示的杠杆效应和再配置效应，本质上是由家庭货币资产结构的变化所驱动的——零售型CBDC直接触发这一机制，而批发型CBDC对家庭端的影响路径更为间接。因此，公共数字货币的设计选择——尤其是其是否直接面向家庭——将决定其对杠杆调整和资本再配置的触发力度，这一结构性差异应在CBDC的设计决策中予以充分考虑。第三，金融科技公司应被纳入监管框架——不是作为补充，而是作为一阶考量。在实际效果上，它们相当于我们模型中的“非银行”，其在货币服务供给中日益增长的角色意味着，它们将越来越决定体系对创新的响应方式。

结论

关于数字货币的讨论框架过于狭窄。核心问题不是稳定币或CBDC谁将胜出，而是：当新的类货币资产——无论是公共发行还是私人发行——进入一个银行不再占主导地位的环境时，金融体系如何调整。理论证据表明，CBDC等公共创新很可能改善金融稳定和福利，而稳定币和金融科技支付服务提供商等私人创新的效应不确定，取决于金融体系的初始结构。在银行主导型经济体中，过渡期可能在带来益处之前先出现不稳定。

现实带来的一大启示，是各类机构都应保持审慎。没有任何单一创新——无论是稳定币、CBDC还是金融科技平台——能独自决定货币的未来。最终结果将由它们之间的互动以及规范这些互动的监管选择所塑造。做出正确的选择，要求我们超越加密监管、中央银行和竞争政策的各自孤岛，建立对货币创新如何重塑金融架构的统一理解。

注释：

[1] Allen F, Walther A. Monetary Innovation and Financial Architecture[R] . Working Paper: Imperial College London and University of Oxford, 2025.

[2] Allen F, Gu X, Jagtiani J. Fintech, cryptocurrencies, and CBDC: Financial structural transformation in China[J]. Journal of International Money and Finance, 2022, 124: 102625.

[3] Atlantic Council. CBDC Tracker[EB/OL].(2026-05-29)[2026-05-29].https://www.atlanticcouncil.org/cbdctracker/.

[4] Buchak G, Matvos G, Piskorski T, et al. The Scale and Regulatory Implications of Shadow Banking[R]. Working Paper, 2024.

[5] Keister T, Sanches D. Should central banks issue digital currency?[J]. The Review of Economic Studies, 2023, 90(1): 404-431.

[6] Whited T, Wu Y, Xiao K. Central Bank Digital Currency and Banks[R]. Working Paper, 2023

□本文根据复旦大学国际金融学院“十五五资本市场高质量发展”闭门研讨会上的演讲和作者最新研究综合整理，仅代表作者个人意见，供读者参考，不作为投资、会计、法律或税务等领域的建议。

□编译 | 潘 琦 复旦大学国际金融学院研究中心

□视觉 | 葛雯瑄 复旦大学国际金融学院研究中心

□图源 | AI辅助生成

Stablecoins, CBDCs, and Fintechs: Rethinking the Debate on Digital Currency

Franklin Allen

Former President of the American Finance Association

Professor of Finance and Economics at Imperial College London

Co-Chairman of the International Advisory Board, FISF

The global monetary landscape is being reshaped by three forces that are often discussed in isolation: stablecoins, central bank digital currencies (CBDCs), and financial technology firms. Each has its own constituency, its own narrative, and its own set of policy preions. Yet these forces do not operate on separate tracks. They interact—sometimes reinforcing one another, sometimes pulling in opposite directions—and the outcome of their interaction will determine the architecture of the financial system for decades to come.

In this article, I argue that much of the current debate frames the issues incorrectly. The question is not whether stablecoins or CBDCs will "win," nor whether digital currencies will "crowd out" banks. The question, rather, is how the financial system adjusts when new money-like assets enter an environment in which banks are no longer the dominant intermediaries. In recent theoretical work with Ansgar Walther (Allen and Walther, 2025), I show that the effects of monetary innovation depend critically on whether the innovation originates in the public sector or the private sector—and that this distinction has been largely overlooked in policy discussions.

Stablecoins: Stability by Name, Instability by Design?

Bitcoin was originally designed as a means of payment, but its extreme price volatility makes it poorly suited for that purpose. Stablecoins—such as the proposed Libra and the implemented Tether—emerged to overcome this limitation by pegging to fiat currencies. Yet the very name "stablecoin" conceals a fundamental tension.

The collapse of Terra-Luna's UST in May 2022 was not an aberration; it was a structural consequence of the interest rate environment. When interest rates were at or near zero, stablecoin issuers needed to invest in risky assets with a positive return in order to cover costs and provide some yield to holders. In doing so, they became risky themselves. Stability, in other words, was conditional on the rate environment—a point that the current regulatory frameworks have yet to fully internalize.

Today, the two most widely used stablecoins illustrate the trade-off between liquidity and compliance. Tether (USDT), with a market capitalization of approximately $190 billion, offers unmatched exchange liquidity and global coverage, yet its reserve composition includes cash, U.S. Treasury Bills, corporate bonds, Bitcoin, and gold, and it lacks full audit transparency. Circle (USDC), with a market capitalization of approximately $77 billion, maintains a reserve composition of cash and short-term U.S. Treasuries, is fully licensed in the United States, and complies with the EU's MiCA regulation. The market has, in effect, bifurcated: one pole optimizes for transaction convenience, the other for regulatory trust.

Regulation has moved quickly on both sides of the Atlantic. The EU's Markets in Crypto-Assets Regulation (MiCA) entered into force in December 2024, establishing a legal framework for stablecoins. The U.S. Guiding and Establishing National Innovation for U.S. Stablecoins (GENIUS) Act was signed into law in July 2025. Both frameworks share a critical provision: they prohibit the payment of interest on stablecoins.

This prohibition is intended to prevent stablecoins from evolving into shadow bank deposits. In joint early-stage work with Angela Gallo, we argue it also creates a latent competitive dynamic that could prove destabilizing. If any jurisdiction allows interest to be paid on stablecoins, funds will flow rapidly toward that jurisdiction's issuers. Competition for deposits may then push issuers toward riskier assets—precisely the dynamic that undermined UST. The parallel with U.S. Regulation Q in the 1960s is instructive: interest rate ceilings on bank deposits drove capital to the unregulated Eurodollar market in London, with consequences that took many years to fully unfold. The same regulatory arbitrage logic applies today, with stablecoins as the vehicle.

CBDCs: The Sovereign Response

If stablecoins represent the market's attempt to improve on fiat payments, CBDCs represent the sovereign's attempt to improve on itself. The pace of exploration has been remarkable: as of May 2026, 146 countries and currency unions are investigating some form of CBDC, up from just 87 in May 2022. Seventy-seven countries are in the advanced stages of exploration—development, pilot, or launch—and 41 pilot projects are currently running worldwide.

Yet numbers can be misleading. Only three countries—the Bahamas, Jamaica, and Nigeria—have fully launched a CBDC, and all three face slow adoption and persistent technical challenges. This suggests that the successful rollout of CBDCs depends not only on technological deployment but also on user acceptance, use cases, and institutional trust.

The two most significant CBDC projects are, however, not in small island economies but in the world's major currency blocs. China's digital yuan (e-CNY) remains the largest CBDC pilot globally: by December 2025, more than 3.4 billion retail transactions worth approximately 16.7 trillion renminbi (about $2.3 trillion) had been processed. Meanwhile, the Cross-border Interbank Payment System (CIPS), authorized by the People's Bank of China, now settles some of its transactions through its own independent channels. SWIFT-denominated numbers alone cannot fully capture the actual scale of e-CNY usage, because they miss the rapidly growing bilateral e-CNY settlements that no longer rely on legacy infrastructure and are instead processed through independent digital channels.

The European Central Bank is advancing the digital euro as a "global euro moment," aiming to strengthen the euro's international role and protect European payment sovereignty. Both the e-CNY and the digital euro, though framed differently, share an underlying logic: the push toward a multipolar currency system. This is not merely a technical project; it also has implications for the international monetary landscape.

Every G20 country except the United States is now exploring a CBDC, with 18 in advanced stages and 14 in the pilot phase. The U.S. position—limited to the New York Fed's wholesale cross-border research through Project Agorá—stands in sharp contrast to its aggressive legislative action on stablecoins. This asymmetry is also related to the position of the U.S. dollar in the existing international monetary system.

What Theory Tells Us: Public vs. Private Innovation

The foregoing discussion raises a question that neither the stablecoin advocates nor the CBDC proponents have adequately addressed: What are the systemic effects when new money-like assets enter a financial architecture in which banks are no longer dominant?

In recent work with Ansgar Walther (Allen and Walther, 2025), we develop a general equilibrium model to address precisely this question. The model features heterogeneous financial intermediaries—banks and non-banks—that compete to provide monetary services to households. In the simplest version, banks benefit from government guarantees; non-banks do not. Households derive utility from monetary services, which are produced by a combination of bank deposits, non-bank bonds, and direct holdings of central bank money. The key endogenous variables are convenience yields on money-like assets, the market shares of banks and non-banks, and the leverage choices of each type of intermediary.

Our central finding is that the effects of monetary innovation depend on whether the innovation is public or private.

Public monetary innovations—such as the introduction of a CBDC that increases households' direct holdings of central bank money—produce clear-cut results. Under mild conditions, a CBDC reduces leverage across the financial system, reallocates investment from banks to non-banks, and decreases financial instability as measured by the probability of bank failure and the expected fiscal cost of government guarantees. The welfare effect is unambiguously positive. The intuition is straightforward: when the central bank provides a competing money—like asset, the convenience yield on bank deposits falls, banks borrow less, their leverage decreases, and their systemic importance diminishes.

This result challenges the widespread concern that CBDCs will "crowd out" financial intermediation. In our model, banks' lending does decline, but non-banks' lending expands concurrently. More importantly, the endogenous decline in bank leverage means that the financial system as a whole becomes more stable, not less. The "crowding out" narrative, while not wrong in a narrow accounting sense, misses the general equilibrium adjustment on the leverage margin.

Private monetary innovations—such as the introduction of a stablecoin or the emergence of FinTech payment providers—tell a different story. Here, the effects are ambiguous and depend on the initial market shares of banks and non-banks. We identify two opposing mechanisms. The first is a debt valuation effect: the innovation increases the convenience yield on non-bank debt, encouraging non-banks to expand. The second is a reallocation effect: as non-banks' willingness to pay for investments rises, the price of capital increases, and investment migrates from banks to non-banks. Since banks are the primary suppliers of monetary services, this migration contracts the overall money supply.

Which effect dominates depends on the starting point. When non-banks already have a large market share—as in the United States, where non-bank lenders supply roughly 60% of aggregate credit—the debt valuation effect tends to dominate, and the outcomes resemble those of a public innovation: expanded monetary services, reduced leverage, improved stability. But when non-banks' market share is initially small—as in bank-reliant economies, or when new FinTech entrants first begin to offer payment services—the reallocation effect dominates initially. The price of monetary services rises in a hump-shaped pattern, banks take on more leverage, and financial stability deteriorates before eventually improving as non-banks become established.

This asymmetry between public and private innovation has, to our knowledge, not been recognized in the policy literature. It suggests that the introduction of stablecoins or FinTech payment providers into bank-dominated financial systems—a category that includes much of continental Europe and many emerging markets—may initially be destabilizing, even if the long-run effects are benign. Policymakers would be well advised to consider this transitional risk.

Fintechs: The Overlooked Third Force

Thus far, the discussion has centered on stablecoins and CBDCs, but there is a third category of actors that is often overlooked in the digital currency debate: financial technology firms. The example of Revolut, the UK-based digital bank, is illustrative.

Revolut is entirely digital, with no physical branches. It offers foreign exchange rates near the wholesale level, savings rates significantly above those of traditional banks, and the ability to transfer U.S. dollars from a UK account to a U.S. account in seconds with no fees. In practice, it outperforms both stablecoins and traditional banks on the dimensions that matter most to users: speed, cost, and accessibility.

This is not an anomaly; it is a structural feature of the new financial architecture. FinTech firms combine the regulatory advantages of banking licenses—including deposit insurance—with the cost advantages of digital operations. It should be noted, however, that this characteristic makes FinTech firms somewhat different from the "non-bank intermediaries" as defined in our model—the latter do not enjoy as strong government guarantees or deposit insurance. FinTech firms are closer to a kind of "hybrid intermediary": resembling non-banks in operational efficiency, but resembling banks in regulatory safeguards. The implication is that licensed FinTech firms, with their combination of low costs, high returns on savings, easy access to products, and deposit insurance, may well become dominant players in the financial system, and their impact on leverage and financial stability may differ significantly from the model's predictions for pure non-bank intermediaries. They should not be ignored.

Rethinking the Debate

The three forces I have discussed—stablecoins, CBDCs, and FinTechs—are typically analyzed in separate policy silos. Stablecoins are treated as a crypto-asset problem; CBDCs as a central banking problem; FinTechs as a competition problem. This fragmentation obscures the bigger picture.

The central lesson from our theoretical work is that the effects of monetary innovation cannot be evaluated in isolation. What matters is thefinancial architecture into which the innovation is introduced—and in particular, the market shares and leverage choices of banks and non-banks. A CBDC that improves stability in a non-bank-heavy system like the United States may have different effects in a bank-heavy system like the euro area. A stablecoin that is benign when non-banks are established may be destabilizing when they are not. And FinTech payment providers that improve user outcomes may, in the transition, trigger leverage adjustments that are prudentially concerning.

The policy implications follow directly. First, regulatory frameworks for stablecoins must anticipate the competitive dynamic created by interest rate prohibitions.The Regulation Q parallel suggests that heterogeneous regulation across jurisdictions will generate arbitrage flows, and that the eventual relaxation of interest prohibitions—if it occurs—should be coordinated rather than unilateral. Second, CBDC design must account for the financial architecture. In a bank-dominated system, a retail CBDC and a wholesale CBDC have different implications for financial stability. The leverage and reallocation effects identified by our model are fundamentally driven by changes in the structure of household monetary assets—a retail CBDC directly triggers this mechanism, whereas a wholesale CBDC has a more indirect impact on the household side. Therefore, the design choice of public digital currencies—particularly whether they are made directly available to households—will determine the intensity of their impact on leverage adjustment and capital reallocation. This structural difference should be given full consideration in CBDC design decisions. Third, FinTech firms should be integrated into the regulatory perimeter, not as an afterthought but as a first-order consideration. They are, in effect, the "non-banks" in our model, and their growing role in monetary service provision means that they will increasingly determine the system's response to innovation.

Conclusion