For the 50 industrial companies in the S&P index, the ratio of the total market capitalization to net earnings is . Aggregate earnings and this price-earnings ratio imply an estimate for the aggregate market capitalization of times GNP. This is slightly higher than Sloan’s (1936) estimate, which was based on a broader subset of industrial companies. To compute an estimate of the total market capitalization using all 90 companies in the S&P composite index, we first construct weights on industrials, railroads, and public utilities using the entire population of companies in the CRSP database for August 1929
