Institutional portfolios have been increasing allocations to unlisted infrastructure investments. However, to fully understand how infrastructure investments can benefit their portfolios, CIOs need better information on the performance and cash flow characteristics of this asset class, as well as a multi-asset, multi-period portfolio construction framework that is fit-for-purpose when allocating to illiquid, private investments alongside liquid, public investments.

Using asset- and fund-level data, we highlight important differences between infrastructure assets and funds, and compare their historical performance and cash flow characteristics with both public and other private investments. An infrastructure asset's age, sector, business risk and corporate structure all influence the asset's risk-return profile. We examine the sensitivity of infrastructure asset and fund performance to public markets by regressing infrastructure returns (at the aggregate, sector and age group level) on public asset market returns.

We then develop a method to estimate infrastructure equity assets' income returns and cash flows depending on their age and sector. With measures defined that capture both idiosyncratic and time-series income return volatility, we highlight that a CIO cannot ignore the high idiosyncratic risk of infrastructure assets when evaluating their future performance and cash flow risk. To reduce a portfolio's idiosyncratic income return risk, we find that adding assets from the same sector may be as efficacious as adding the same number of assets from different sectors. We show how many assets are needed before idiosyncratic income return risk starts to level off.

To help CIOs make better-informed decisions regarding their allocations to infrastructure, we incorporate our infrastructure cash flow models into PGIM IAS' asset-allocation framework (OASIS). We analyze the performance and liquidity risk of portfolios with different allocations to infrastructure investments and other private assets and demonstrate that infrastructure investments, especially infrastructure assets, could improve portfolio diversification and liquidity, driven by their relatively large and stable income return.