This document discusses using firm-level microdata to identify markets that may have competition problems and examines productivity as a potential indicator. It outlines competition indicators constructed from UK business data and finds that some match sectors previously studied. However, limitations include SIC codes not perfectly matching markets. The document also explores using relative productivity between sectors as a indicator but finds the measure has limitations like unstable survey data and no clear relationship with competition measures. Potential next steps discussed are longer time series, imports/exports as scope proxy, and total factor productivity.