What is Spend Concentration?

Spend Concentration is budget inequality across campaigns, measured with a Gini Index — a value near 1 means one campaign is a billionaire while the rest starve; above 0.6 is dangerously concentrated.

Why it matters

Concentration is a portfolio risk: overfed campaigns hit diminishing returns while efficient campaigns run out of budget before the day ends. The account's best performers are throttled to feed its loudest ones.

How ClickCatalyst detects it

The Gini Index is computed over campaign spend exactly as economists compute income inequality. Overfed campaigns are those spending more than 2x the account average; starved campaigns convert cheaply but exhaust their budget early.

Every campaign is graded in a Rebalance Matrix — SCALE (outperforming and budget-limited), CUT (underperforming and overfed), UNDERFUND (decent but severely limited), HOLD (everything else) — and a budget-transfer simulation projects the net gain of moving money from CUT to SCALE. A Maturity Rebalance Guard protects campaigns still in the learning phase from being cut prematurely.

Gini = 1 − (2 × SUM(spend_i × (n − rank_i + 1)))
            ÷ (n × total_spend)

Bands: > 0.6 dangerous concentration
Overfed: campaign_spend > 2 × mean_spend

Example

An account with a 0.7 Gini where the overfed campaign is NOT the best performer is paying twice: diminishing returns on the hog, lost conversions on the starved winners.