One firm made 41% of the panel's investment; three made 76%

How concentrated was investment among the eleven Grunfeld firms? Each row is one firm, summarizing its twenty years from 1935 to 1954: total investment, mean investment, and mean market value, in millions of 1947 dollars. Every firm has the same 20 years, so a bigger total is a bigger firm, not a longer record.

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General Motors alone was 41% of the total

Rank the firms by twenty-year total investment. General Motors invested $12,160 million, 41.46% of everything the panel spent. General Motors and US Steel together account for 69.45% of cumulative panel investment, and the three largest firms together account for 76.43%. The bottom five firms are slivers.

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Investment scaled with market value

Each point is one firm, placed by its mean market value and mean investment. General Motors sits alone at the top right, with a mean market value of $4,334 million. The fitted line runs through the other ten, which cluster below $2,000 million in value and $110 million in yearly investment.

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Relative to its size, US Steel invested hardest

Divide each firm's mean investment by its mean market value. US Steel invested $20.82 per $100 of market value each year, General Motors $14.03, and General Electric, the third-largest investor in dollars, only $5.27. Union Oil and Atlantic Refining, small in dollars, invested the most for their size.

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Takeaway

Three of eleven firms made three-quarters of the panel's investment, and General Motors alone made two-fifths. Any pooled statistic on this panel is mostly a statistic about General Motors and US Steel. For how hard a firm invested, scale by its size: on that measure, the oil companies and US Steel lead.

Limits

Eleven firms chosen for a 1958 textbook, so the denominator is the panel, not American industry. Market value is a mean of twenty year-end figures, and summing it across years would not be a stock of anything, so only investment is totaled.