where ei,t
C is the deviation from the CIP observed for i period
bonds at time t for bonds denominated in a given
foreign currency measured against comparable US dollar
rates. Recognizing that alternating periods of positive
and negative deviations from parity could offset each
other and translate into average deviations close zero,
Popper focuses her statistical analysis on the mean absolute
deviation (MAD) from parity measured for each
pair of bond yields rather than the magnitude of their
simple average deviations. She finds MADs that are
larger on average for long-term bond yields than
short-term Eurocurrency rates, and larger for onshore
government bond yields than offshore corporate Eurobond
yields. Even so, given the considerable variability
in the MADs that she observes, Popper is typically unable
to find evidence that the MADs she estimates are
statistically different from one another (or zero) in magnitude.
As a result, she concludes that capital is equally
mobile across borders in both short-term and long-term
capital markets, and onshore and offshore bond markets.
Taking advantage of more than a decade’s worth of
advances in both the underlying markets and data
availability, McBrady (2002) reexamines the same questions
Popper addresses with a much broader data set. He
estimates MADs for a comprehensive set of bond yields
of varying currency, credit quality, and maturity. Importantly,
he also estimates all MADs in a joint specification
that accounts for the considerable persistence observed
in the data. Overall, McBrady concludes that deviations
from the CIP are larger for onshore government benchmark
bonds than offshore corporate Eurobonds, and
larger as a whole for bonds than short-term currency
markets. Among corporate Eurobonds, he also finds that
deviations are a decreasing function of credit quality and
an increasing function of maturity. Updated data on a
subset of the deviations from parity that McBrady analyses
for the five most common international currencies
are presented in Figures 15.1–15.3. As evident in the figures,
deviations from parity do appear to differ significantly
across currencies, suggesting time-varying
opportunities for bond issues to exploit relatively lower
foreign currency borrowing costs through opportunistic
issuance.
Fletcher and Taylor (1996) and McBrady (2004) take
the analysis one step further. Rather than simply measuring
the magnitude of deviations from parity, they offer
more sophisticated analyses that directly incorporate
the effects of transaction costs. Fletcher and Taylor incorporate
direct measures of the bid–ask transaction costs
incurred by one-way arbitrageurs and find that deviations
from parity are on average smaller in magnitude.
On the other hand, they find that deviations from the
CIP in excess of bid–ask transaction costs are neither rare
nor short lived. Interestingly, they also find that the variance
of measured deviations from the CIP is a decreasing
function of the time spent outside of the ‘neutral
band’ established by transaction costs, suggesting that
some type of one-way covered interest arbitrage serves
to bring bond yields and currency swap rates closer to
parity in equilibrium.
McBrady (2004) performs a similar analysis on a
broader data set of corporate Eurobond yields, government
benchmark yields, and short-term currency rates.
Adopting a methodology frequently used to assess the
integration of traded goods markets, he fits a threshold
autoregression model of deviations from parity. The
model provides direct estimates of the width of noarbitrage
neutral bands and the half-lives of deviations
from parity that fall outside them. Overall, he finds that
both measures of capital mobility and market integration
suggest that longer term, lower credit quality bonds
are markedly less integrated than short-term currency
markets. Unlike Popper’s findings (and consistent with
the evidence in Figures 15.1 and 15.2), McBrady also
finds that government benchmark bond markets appear
the least integrated of all. On the other hand, McBrady
finds that relatively short-term high-grade corporate