Geographic Diversification — US, Korea, Emerging Markets

What is Geographic Diversification?

Geographic diversification involves distributing equity assets across multiple countries to prevent overall returns from being overly dependent on the economic, policy, or currency risks of a single nation. Even within the same industry, stocks listed in different countries will have distinct interest rates, exchange rates, and regulations, causing their price movements to diverge. Simply increasing the number of individual stocks is not enough; you must increase the number of 'countries' to which you are exposed.

This topic is particularly important for Korean investors due to home bias—the tendency to overweight domestic assets simply because they are familiar. While Korea's share of the global stock market is in the low single digits, many domestic portfolios hold more than half of their assets in Korean stocks. This article serves as educational material, covering the principles for addressing this imbalance.

Why Diversification Reduces Risk — The Principle of Correlation

The core of diversification's effectiveness lies in correlation. If two markets always move in the same direction, their correlation coefficient is close to +1, and combining them will hardly reduce volatility. As their movements diverge, the correlation coefficient decreases, meaning that when one market falls, the other may hold steady, smoothing out overall fluctuations. Different countries typically have different economic cycles and currencies, leading to lower correlations.

Let's look at a simple example. Suppose the annual expected return for stocks in Country A and Country B is 8% each, and their volatility (standard deviation) is 20% each. If the correlation coefficient is 1, combining them 50:50 still results in 20% volatility. However, if the correlation is 0.3, the volatility of the same combination drops to approximately 16%. The goal of geographic diversification is to reduce risk while maintaining the same expected return of 8%.

Exchange rates are also part of diversification. Holding US stocks means holding dollar-denominated assets. When the Korean won weakens (meaning the KRW/USD exchange rate rises), currency gains can partially offset stock price declines. However, this is a double-edged sword, as it can also work in reverse.

US, Korea, Emerging Markets: Characteristics of Each Block

The US market, with its largest market cap and numerous large companies with significant global revenue, serves as a core block broadly linked to the global economy. Its currency, the dollar, attracts safe-haven demand during crises, but frequent periods of high valuations mean entry prices should be carefully considered.

The Korean market, with its high concentration in export-oriented manufacturing sectors like semiconductors, automobiles, and chemicals, is sensitive to global economic conditions and trade volumes. For domestic investors, advantages include easy access to information and convenience in taxes and currency exchange, but it means concentration in a single country's industrial structure. Emerging markets offer high growth potential but come with higher volatility due to political, currency, and liquidity risks.

Leadership among these three blocks shifts depending on the economic cycle, and it's difficult to predict future winners in advance. Therefore, distributing assets across multiple blocks and managing their weights is the starting point for diversification.

Practical Criteria for Setting Allocations

A commonly used criterion is market cap weighting, which means simply following the proportions of the global market. Under this approach, the US accounts for over half, while Korea remains in the single digits. Many compromise solutions allow for some home bias, adding a slightly larger allocation to Korea. This might involve starting with a hypothetical allocation like US 50%, other developed markets 20%, Korea 20%, and emerging markets 10%, then adjusting as needed.

Allocations are not set once and forgotten; they should be regularly rebalanced. If one block significantly outperforms, its weight will exceed the target, leading to concentrated risk. The process of restoring it is rebalancing. If a target allocation is 50% but grows to 60%, you would trim the excess and reallocate to underperforming blocks, establishing the discipline of 'selling what has risen and buying what has lagged.'

ETFs that track country or regional indices are convenient tools for implementation. They allow you to gain exposure to an entire block without selecting individual stocks, enabling diversification with fewer transactions.

Common Pitfalls and Limitations

First, what appears to be diversification often isn't. Even if you hold both Korean large-cap stocks and US tech stocks, if both are tied to the global semiconductor and IT cycles, they may fall together during a crisis. The key is not the 'number' of countries, but whether the underlying risk factors overlap.

Second, during crises, correlations can temporarily approach 1. Even markets that usually move independently may fall together when fear spreads. Therefore, geographic diversification is a mechanism to reduce everyday volatility, not a shield against all market crashes. Costs such as currency hedging and capital gains taxes on foreign stocks can also reduce net returns.

Third, excessive diversification can increase management costs and tracking difficulty. If blocks are too finely divided, rebalancing becomes cumbersome, and it's hard to understand what you're exposed to. The purpose of diversification is risk control, not simply increasing the number of holdings.

Summary and Checkpoints

Geographic diversification is a strategy to reduce correlation and volatility by distributing assets across markets with different economic cycles and currencies. The key is not the number of individual stocks, but exposure to non-overlapping risks, and maintaining target allocations through rebalancing.

There are three checkpoints. Is your Korean allocation excessively high compared to its weight in the global market? Are your investments in other countries still tied to the same industry or currency risks? How far have your allocations drifted from your targets? Specific allocations should be determined based on individual investment horizons and risk tolerance.