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N° 2000 - 04 |
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| February |
The Expectations of Hong Kong Dollar Devaluation
and their Determinants |
| Bronka Rzepkowski |
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During the Asian financial turmoil over the
1997-1998 period, only the Hong Kong dollar peg escaped the wave of huge devaluations
which hit Asian currencies. But speculative pressures did not spare the Hong Kong
currency board. Indeed, several attacks were launched against the Hong Kong dollar
and the expectations of devaluation fluctuated sharply over the period. The motivation
of the paper is threefold.
First, it deals with the key determinants driving the expectations of
a possible breakdown of the peg in a VAR framework. It uses currency options on the Hong Kong dollar to estimate the expected probability and intensity
of devaluation over a one-month horizon, from February 1997 to the end of 1998. Because Hong Kong did not suffer from bad fundamentals at least
in 1997, which could have justified the attacks against its currency, one explanation to the observed speculative pressures rests on possible
contagion effects stemming from the Asian crisis. To account for the propagation of shocks, three possible channels can be emphasized: a common cause stemming
for example from the industrial countries and affecting the emerging economies in the same way (monsoonal or external effects), a crisis in one country
entailing a modification of macroeconomic fundamentals in another (spillover effect), and the shift in market sentiment about the fundamentals of a
country triggered by a crisis elsewhere, which is a pure contagion effect. These three channels of propagation are tested, the variables aiming at
capturing these effects being introduced with an exogenous status.
Second, the paper focuses on the cross-market speculation, which involved
the stock exchange and the markets of Hang Seng Index (HSI) futures and options, in addition to the foreign exchange market. The way the speculation
worked in Hong Kong during the 1997-1998 period is closely linked to the operation of the Hong Kong currency board, where an automatic adjustment
mechanism links capital inflows and outflows to the overall level of liquidity in the banking system. The predictable sensitivity of interest rate to
capital flows was exploited by some speculators who engaged into the so-called "double play": they entered the money market to borrow huge
amounts of HK dollar, then short-sold stocks and HSI futures abruptly before shorting Hong Kong dollar. The HK dollar sell-off wave was aimed
at provoking a spike in interest rates, then forcing the stock exchange to plunge. To measure the impact of such speculative dynamics on the expectations
of a HK dollar devaluation and the extent to which the expectations of a peg breakdown fuelled the double play, three endogenous variables were
introduced in the VAR: the intensity of devaluation, the HSI futures prices and the implied volatility of the stock index.
Third, the paper shows that the significant determinants originating
the expectations of devaluation in Hong Kong as well as the pernicious speculative dynamics are important factors in order to understand both
the interventions of the Hong Kong Monetary Authority (HKMA) and the reform of the currency board in September 1998. Over the period, the Monetary
Authority changed its strategy to defend the peg. In a first place, the measures undertaken relied on discretion and were aimed at influencing
different market prices. The most controversial action was its interventions in the stock and HSI futures markets in August 1998. Then, a reform was
undertaken to strengthen the currency board, which basically consisted in grounding the regime on a more rule-based system. The impact of the
different measures on the expectations of a HK devaluation are assessed via dummies introduced in the VAR.
Three major conclusions can be drawn. First, only two channels of shock
propagation are plainly robust and significant in explaining the formation of expectations on the HK dollar: the external effects of a world shock,
observed and expected, captured by the value of the dollar/yen exchange rate and by its expectations, and the pure contagion effects relying on
the reassessment of risk by international investors. Second, the presence of a double play is made clear. The impulse response functions underline
the circularity of expectations: the expectations of a HK dollar devaluation fuelled speculation in the stock futures and options markets, which in
turn was conducive to fears of an impending demise of the currency board. Third, the reflexivity in the formation of expectations led the HKMA to
engage in unusual interventions, departing from its traditional free-market philosophy. All the discretionary measures adopted by the HKMA to break
this self-fulfilling speculative scheme proved to be ineffective. In contrast, when the HKMA undertook reforms to introduce a more rule-based system
in September 1998, it succeeded in dampening the pressures against the HK dollar. |
Abstract |
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| Currency Board, Hong Kong, speculative attack,
probability density functions, contagion |
Keywords |
| E42, E58, F41 |
JEL classification |
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