positively related to holding costs that can impede arbitrage,
even after controlling for a variety of transaction
costs, taxes, and foreign investment restrictions. The
holding cost proxies they considered include the stock
pair’s idiosyncratic risk that is unrelated to the risk of
other securities in either of the competing markets; the
stock’s dividend yield, which can lower holding costs;
and interest rates, which represent an opportunity cost
of capital, since arbitrageurs usually do not receive full
interest on short-sale proceeds. Among these proxies,
they found that idiosyncratic risk has a statistically reliable,
positive relationship to price parity deviations
across stock pairs and over time, and that it is economically
the most important holding cost. Together, these
factors explain over 20% of the cross-sectional variation
in the levels of and changes in price deviations across
their broad sample of cross-listed pairs.
A potential weakness of Gagnon and Karolyi’s study,
as well as of those that came before it, in studying the deviations
from price parity in cross-listed stocks is the fact
that they focused on systematic patterns across stocks
and across time that can mask or ‘average out’ potentially
important episodes during which time these deviations
can be most acute. An intriguing study by
Rabinovitch et al. (2003) evaluated the returns spreads
between 14 Chilean and another 6 Argentinean homemarket/ADR
pairs. But they employed a nonlinear multiple
time-series technique (STAR, smooth transition
autoregressive) that allows for nonlinear convergence
among the two competing stocks in response to deviations
from price parity. What they showed is that the
average magnitude of the spreads was much lower
(1.14% for Argentina compared to 1.37% for Chile) and
the intensity of the mean reversion process was much
higher among the Argentinean pairs. They attribute this
result to the fact that Argentina had a currency board regime
fixing the Argentinean peso to the US dollar,
whereas Chile had a freely floating regime throughout
their period of study.9 Two follow-up studies by
Melvin (2003) and Auguste et al. (2006) offered a clinical
study in Argentina of how the size of the arbitrage gaps
(in the form of an ADR price premium relative to the underlying
ordinary shares) widened dramatically around
Autumn 2002 when there was an expected peso devaluation
and the government imposed capital controls
(‘corralito’ regime).
Another study by Blouin et al. (2009) uncovers another
fascinating episode in which deviations from price
parity widen dramatically. They examined the role of
shareholder-level taxes and specifically the unexpected
reduction in US capital gains taxes around the
announcement of the 1997 budget accord in the US Congress.
These announcements changed the pricing of the
cross-listed shares relative to the home-market ordinary
shares widening the gaps by 40 basis points, on average.
Finally, exploiting the natural experimental setting created
by the short-sale ban of 2008 in the middle of the financial
crisis in the United States, Gagnon and Witmer
(2011) uncovered an even more dramatic increase in deviations
from price parity among Canadian bank stocks,
which were subjected to the short-sale prohibition both
in the United States and at home during the period.
Using the difference-in-difference panel regression methodology,
they documented a 74 basis-point increase, on
average, in the price gap between the United States and
the home market during the ban and, after the ban was
lifted, they observed a reversal of the price gaps back to
near parity, where they stood before the ban. Such studies
involving interesting episodes or shocks to multi-market
trading settings have great potential for helping our understanding
of the true price dynamics governing such
securities.