Oligopoly

Concentration indices.

Hirschman-Herfindahl Index (HHI).

wIncludes all firms in the market.

i = 1

Si

Σ

H =

m

2

Albert O. Hirschman, 1915-

wWeights contributions of largest firms more.

wRanges between 0 (perfect competition) and 10,000 (monopoly).

× 10,000