Competition policy investigations usually commence with a definition of the relevant product and geographic market. The relevant market provides a first evaluation of competitive conditions and allows for the calculation of market shares, which aids in the assessment of firms’ market power....

Various quantitative tools have been developed for defining markets in competition law investigations. Econometric tests on price co-movement represent one such set of tools: two regions or products are considered part of the same market if their prices co-move. However, price co-movement tests,...