The term blended finance implies the mixing of both public and private funds through a common investment scheme or deal, with each party using their expertise in a complementary way. The concept and model was developed within the Redesigning Development Finance Initiative from the World Economic Forum, who defined it as "the strategic use of development finance and philanthropic funds to mobilize private capital flows to emerging and frontier markets."^[10]

The resources needed to bridge the funding gap to meet SDG requirements cannot be met through public resources (such as Official Development Assistance) alone, and private investment will be key to increasing the scope and impact of development finance and philanthropic funders. Only a small percentage of the worldwide invested assets of banks, pension funds, insurers, foundations and endowments, and multinational corporations, are targeted at sectors and regions that advance sustainable development. This is due to the fact that large-scale investing usually flows into environmentally destructive activities that come with higher economic incentive.^[11] The current challenge for the SDG era is how to channel more of these private resources to the sectors and countries that are central for the SDGs and broader development efforts. This is particularly important in a context where public resources are increasingly under pressure, while private flows to developing countries are increasing significantly. Blended finance is designed to fuel vast inflows of private capital to support these development outcomes.

Investors and commercial institutions are increasingly attracted to emerging and frontier markets,^[12] and this trend overlaps with the challenges faced by development funders, who face significant financial constraints and a lack of capacity or expertise in structuring transactions or sourcing deals. Thus, there is a good opportunity for these two trends to converge and there is a political will for effective public-private collaboration, presenting a real opportunity for investors and financiers to develop more effective strategies for managing their participation in emerging markets. Blended finance contributes to development objectives by:

1. Increasing capital leverage: Extends the reach of limited development finance and philanthropic funds as they are used strategically to facilitate larger volumes of private capital that are channelled to investments with high development impact
2. Enhancing impact: The skillsets, knowledge and resources of public and private investors can increase the scope, range, and effectiveness of development-related investments.
3. Deliver risk-adjusted returns: Risks can be managed to realise returns in line with market expectations, catalyzing private funds to development projects.

Supporting mechanisms have been traditionally used by development funders in a Blended Finance package to attract and support private sector investors by managing risks and reducing transaction costs. These mechanisms can generally be classified as providing:

• Technical Assistance, or grant funds to supplement the capacity of investees and lower transaction costs.
• Risk Underwriting, to fully or partially protect the investor against risk through appropriate risk mitigation
• Market Incentives, guaranteed payments contingent on performance of future pricing and/or payment in exchange for upfront investment in new or distressed markets.

The Sustainable Development Investment Partnership,^[13] Convergence,^[14] and THK^[15] are three platforms that put blended finance into practice. Their goal is to bring relevant entities from the public and private sector together, connecting interests and resources to initiatives. Both of these platforms provide capital suppliers with access to a pipeline of individual blended finance project transactions, effectively scaling up the participation of both public and private investors in transactions. THK (Tri Hita Karana) began as a roadmap that was launched as a unified, international framework for mobilizing additional commercial capital towards the Sustainable Development Goals (SDGs), and was recently converted into a Blended Finance platform in 2021.

Community of Practice on Private Finance on Sustainable Development^[16] brings together Development Assistance Committee members and private sector.

While blended finance is showing promising initial interest and results, these platforms will help assess the efficiency of the model over time.

• Social Impact Incentives