A second anomaly is that cycles exist in both the volume and the average initial
returns of IPOs. This is illustrated using U.S. data in Figures 1 and 2. The periods
of high average initial returns are known as 'hot issue' markets, and were first
documented in the academic literature by Ibbotson & Jaffe [1975].
Rational explanations for the existence of hot issue markets are difficult to come
by. Ritter [1984a] hypothesizes that 'changing risk composition' might be able to
account for the dramatic swings in average initial returns, since cross-sectionally,
riskier issues tend to be underpriced to a greater extent. If there are some periods
in which the firms going public are riskier than in other periods, the periods with
the riskier firms will have higher average initial returns. Ritter finds that although
there is some evidence that the hot issue periods are characterized by riskier
issues, the amplitude of the cycles in average initial returns is far larger than
can be accounted for by the changing risk composition hypothesis. Instead, the
high average initial returns for the 15-month period starting in January 1980 are
primarily due to the effect of a single industry: oil and gas stocks. Many of these oil
and gas offerings were 'penny stocks', with offering prices of less than $1.00. These
offerings generally had low market capitalizations, so that if the average initial