This raises a central question for the impact economy: why do many of the most promising financial innovations struggle to move from concept to widespread use?

This article examines one such innovation — Flexible Low Yield (FLY) paper — not simply as a proposed instrument, but as a lens through which to understand the persistent gap between financial design and market adoption.

FLY paper: a bespoke hybrid investment mechanism

In Social Enterprise Law, Brooklyn Law School professor Dana Brakman Reiser proposes FLY paper as a form of convertible or contingent debt tailored to social enterprises. The instrument offers investors a modest (low) yield alongside a conversion right into equity triggered under specific conditions, such as a sale of the enterprise.

This structure is designed to align incentives between entrepreneurs and investors. By allowing investors to capture a portion of upside in the event of mission drift or sale, it makes “selling out” less attractive and helps reinforce long-term commitment to the social mission. In this sense, FLY paper aims to make mission “sticky” by tying financial returns to the enterprise’s sustained social purpose rather than short-term profit extraction.

For many impact investors, the challenge is not a lack of innovative tools, but determining which structures are sufficiently credible, scalable, and aligned with real-world market behavior.

In theory, FLY paper offers several advantages. It can be layered onto a range of hybrid social enterprise structures (including PBCs, L3Cs, and CICs), provides predictable returns that may be treated as debt for tax purposes, and offers built-in protections that may reduce perceived risk for mission-aligned investors. For tax-exempt or philanthropic investors, it may also align well with program-related or mission-related investment strategies.

At the same time, FLY paper is inherently bespoke. Its terms must be negotiated within a highly specific, mission-driven context, and its structure requires a level of sophistication from both entrepreneurs and investors. While not fundamentally foreign to experienced market participants, its complexity raises important questions about how easily such instruments can move beyond niche applications.

Appealing to whom?

FLY paper could offer particular value to early-stage or small-to-medium social enterprises seeking to demonstrate credible commitment to mission while accessing capital. For entrepreneurs, it may serve as both a financing mechanism and a signaling tool — communicating seriousness about long-term impact to prospective investors.

For new mechanisms to take hold, they must become legible to investors, workable for entrepreneurs, and compatible with the systems through which capital flows.

On the investor side, the instrument may appeal to patient, mission-driven capital providers who are unwilling to fully subordinate financial returns but are seeking structures that balance financial yield with social outcomes. Philanthropic foundations, for example, might use FLY paper in program-related investments or as part of mission-aligned endowment strategies.

Even if it remains limited to relatively specialized contexts, FLY paper and similar bespoke instruments can play an important role as testing grounds. They allow entrepreneurs and investors to experiment with new ways of aligning capital and mission without relying on regulatory change or the success of any single legal form.

Why promising innovations struggle to scale

The more instructive question, however, is not simply whether FLY paper works in theory, but why mechanisms like it so often struggle to gain broader traction.

FLY paper faces several of the same persistent challenges that affect many forms of impact finance innovation.

• Complexity and novelty. Compared to standard debt or equity instruments, FLY paper is more elaborate and lacks widely recognized templates. Without standardization, each deal requires significant negotiation, limiting scalability.
• Transaction costs and required sophistication. Crafting and negotiating bespoke instruments can be expensive and time-consuming. As Professor Brakman Reiser notes, the costs of designing a FLY paper investment may “swamp the deal size,” particularly for smaller enterprises.
• Limited investor familiarity and demand. Without a track record of successful implementation, investors may hesitate to adopt unfamiliar structures, even when they are conceptually appealing.

Taken together, these constraints point to a broader pattern: financial innovation does not scale simply because it is well designed. It scales when it aligns with how capital markets operate — through standardization, familiarity, and repeatability.

This helps explain why many bespoke, mission-aligned instruments remain confined to niche contexts, even when they address real needs.

From bespoke innovation to market adoption

For FLY paper to move beyond a limited set of use cases, it would likely need to evolve in ways that reduce friction and increase accessibility.

At the urban edge, financial innovation becomes visible in the systems that shape everyday life — where partnerships between entrepreneurs and local institutions determine how capital is translated into infrastructure at scale.

This could include the development of standardized templates, integration into platforms such as debt crowdfunding or peer-to-peer lending networks, and the emergence of third-party validators capable of certifying mission alignment. Over time, such developments could transform FLY paper from a negotiated, case-specific instrument into a more recognizable and replicable product.

At the same time, this pathway highlights a fundamental tension within the impact economy. The very features that make bespoke instruments attractive — flexibility, mission specificity, and tailored alignment — are often the same features that inhibit scale.

The challenge, then, is not simply to design better instruments, but to build the supporting infrastructure that allows those instruments to be used more widely.

The challenge, then, is not simply to design better instruments, but to build the supporting infrastructure that allows those instruments to be used more widely.

A valuable tool — and a broader lesson

FLY paper represents a thoughtful addition to the evolving toolkit of mission-aligned finance. Whether or not it achieves widespread adoption, it contributes to the ongoing experimentation that is shaping how capital can be aligned with social purpose.

More importantly, it illustrates a broader lesson for the impact economy.

Innovation in financial design is necessary, but not sufficient. For new mechanisms to take hold, they must become legible to investors, workable for entrepreneurs, and compatible with the systems through which capital flows.

Without that translation from bespoke innovation to market infrastructure, even the most promising ideas risk remaining, quite literally, on paper.