Economists and finance specialists have long studied stock markets. Some have tried
explaining its determinants, while others have studied regional and international linkages, all
in a bid to better explain and predict returns. The relationship between stock returns and
different macroeconomic fundamentals has been analyzed following the Arbitrage Price
Theory (APT) established by Ross (1976) and later extended by Connor and Korajczyk
(1986). The attempt was to model expected returns as a function of various macroeconomic
factors. The general conclusion of the theory is that an additional component of long-run
return is required and obtained whenever a particular asset is influenced by systematic
economic news and that no extra reward can be earned by bearing diversifiable risk.
However, the APT does not in itself say which factors explain returns best or even if they
capture the entirety of the situation, which is more of an empirical question. It has been
silent about the identity of these necessary factors in trying to determine stock market
returns. After a decade, Chen et al. (1986) posited that five economic variables—industrial
production, unanticipated inflation, changes in anticipated inflation, twist in the yield curve
and changes in risk premium—are plausible sources of common variation among equity
returns. Their cross-sectional regression-based empirical study finds that industrial production,
anticipated inflation and risk premium are significant factors. Evidence for the remaining
were mixed and varied with the period of investigation, importantly the New York Stock
Exchange on which the testing was done despite being a weighted index could not significantly predict future time series variability of its’ own returns. A problem with the approach was
that the variable selection was very subjective. Subsequent literature has tried to identify and
explain a few variables which by and large explain stock market returns in a country. This
practice in tune with the APT makes the residuals as small as possible, so as to minimize the
unexplained or arbitrary part of the stock returns. The theory highlights the below listed
variables the most:
Inflation: Theory by and large gives two views on relation between inflation and stock
returns. The first and earlier view draws on Fisher (1930), who stated that expected rates
of return consist of a ‘real’ return plus the expected rate of inflation and the real return
does not move systematically with the rate of inflation. In short, investors will on average
be fully compensated for erosion in purchasing power. However, another view supported
by Geske and Roll (1983) argues that a rise in expected inflation rate leads to restrictive
monetary policies, which would increase the interest rates and hence have a negative
effect on stock market activity. The effect of high interest rates would not be neutralized
by an increase in cash flow resulting from inflation, but cash flows do not grow at the
same rate as inflation. Hence, theoretically it is still a matter of debate (Fama, 1981).
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