Hall, Bronwyn H. "The Stock Market's Valuation of R&D Investment During the 1980s." American Economic Review, May 1993.

The author argues that "although intangible R&D assets from 1973 through about 1983-84 were about equally valued with tangible capital, this relationship completely broke down in the mid-1980s." The author speculates that this might be due to a shift in market preferences to consumer companies (which have low rates of R&D spending) because they were deemed to be takeover candidates.