
P1: OTA/XYZ P2: ABC
JWBT468-c11 JWBT468-Burghardt March 12, 2011 2:0 Printer Name: Courier Westford
Measuring Market Impact and Liquidity 237
in the market allows. The effect on the spread, however, is proportional to
the square root of the order size. Thus, a quadrupling of the order size only
doubles the size of the spread. Trading volume, the square root of which
appearsinthedenominator,worksinthesamewayasordersizebutinthe
opposite direction. A quadrupling of useable trading volume in the market
would cut the spread in half.
As a practical matter, compensation per contract in this exercise would
be one half the bid/ask spread for orders of any given ...