Growing Oligopolies, Prices, Output, and Productivity
利用1972-2012年美国普查数据，研究发现行业集中度上升与生产率及实际产出增长正相关，与价格变化无关，与劳动收入份额负相关，表明生产率高的寡头企业扩张产出、压低价格，提升消费者福利但降低劳动份额。
American industries have grown more concentrated over the last 40 years. In the absence of productivity innovation, this should lead to price hikes and output reductions, decreasing consumer welfare. With US census data from 1972 to 2012, I use price data to disentangle revenue from output. Industry-level estimates show that concentration increases are positively correlated to productivity and real output growth, uncorrelated with price changes and overall payroll, and negatively correlated with labor’s revenue share. I rationalize these results in a simple model of competition. Productive industries (with growing oligopolists) expand real output and hold down prices, raising consumer welfare, while maintaining or reducing their workforces, lowering labor’s share of output.