Portfolio

Income Concentration

Measure tenant concentration risk using share analysis and a Herfindahl index.

Intermediate

Introduction

Who this is for: Portfolio and multi-let investors assessing income risk.

Why it matters: A portfolio yielding 7% from one tenant is a fundamentally different asset from one yielding 7% from twenty. Concentration is the risk that does not show up in the yield.

Typical scenario: A multi-let estate where the anchor tenant provides nearly half the income.

Common mistakes:
  • Counting tenant numbers rather than income share.
  • Ignoring that several units let to the same group are one covenant.
  • Treating a strong covenant as removing concentration risk — it reduces default probability, not exposure.

Inputs

Tenant Income

£
£
£
£
£

Cost Base

£

Analysis

Across 5 tenants producing £200,000, the largest provides 47.5% and the top two 68.5%. The concentration index of 0.305 rates this portfolio as concentrated — equivalent to 3.3 equally-sized tenants.

This analysis provides context, not financial advice. Consult a qualified adviser before making investment decisions.

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Sensitivity Analysis

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Live Results

Largest Tenant Share

47.50%

Top Two Share

68.50%

Concentration Index

0.31x

Net Income if Largest Lost

£67,000

The largest tenant provides 48% of income. Losing them would leave £67,000 after fixed costs.
A concentration index of 0.305 indicates a concentrated income profile — effectively equivalent to just 3.3 equally-sized tenants.
Total Income£200,000
Tenants5.00x
Effective Tenant Count3.28x
RatingConcentrated