2023-05-19 49 英文报告下载
NAICS’s 6-digit codes are the most finely grained U.S. government industry classifications. The Census Bureau divides the economy into 1,057 industries in this classification. Using 6-digit NAICS codes and Census data, the Information Technology and Innovation Foundation (ITIF) found that the average C4 ratio (the share of sales captured by the top four firms in an industry) increased by just 1 percentage point from 2002 to 2017, from 34.3 percent to 35.3 percent.12 Only 4 percent of U.S. industries were highly concentrated in 2017, with the share of industries with low concentration growing by around 25 percent from 2002 to 2017. In addition, as shown in figure 1, the more concentrated an industry was in 2002, the higher the likelihood it became less concentrated by 2017. The fact that the concentration has not been growing overall is a major blow to the foundational tenet of Philippon’s theory.
Regarding the EU, granular concentration data is not accessible. With what evidence we do have, it seems that concentration has been slightly increasing in narrowly defined product markets. Researchers from the Center for Economic and Policy Research conducted a comprehensive study of concentration levels in 20,000 EU markets. They found that “concentration has increased over time on average [in the EU].”16 The report finds that “average concentration is particularly high in narrowly-defined national markets” and that concentration has more steeply increased in EU-wide markets.17 In other words, when researchers use proper market definitions, they show that Europe is not seeing a significant decline in market concentration over time, as Philippon claims. While European antitrust deters many efficient combinations, it is not actually driving down average market concentration, as Philippon claimed.