Many Korean investors invest only in domestic stocks — familiar names like KOSPI, Samsung Electronics, or Kakao. But I invest 80% of my portfolio in foreign stocks. The reason is simple: the Korean stock market represents just 1.6% of the global market (MSCI, 2023).
What Is Global Diversification
Global diversification means spreading investments across assets in multiple countries and regions. If one country’s economy falters, others compensate. According to Harry Markowitz’s Modern Portfolio Theory (MPT), combining assets with low correlation yields higher returns for the same level of risk (Markowitz, 1952).
Related: evidence-based supplement guide
Home Bias: The Data Behind the Trap
Despite Korea representing just 1.6% of global market cap, Korean investors on average hold over 60% of their portfolios in domestic stocks (Vanguard, 2020). This is home bias — and it’s a global phenomenon, not just a Korean one.
Vanguard’s research across 9 countries found that investors consistently over-allocate to domestic markets by 3 to 5 times their market-cap weight (Vanguard, 2020). Australian investors hold 67% domestic (Australia = 2.4% of global market cap). Japanese investors hold 55% domestic (Japan = 6.7% of global market cap). The pattern is universal.
The psychological roots are well-documented: familiarity breeds perceived safety. We feel we “understand” Samsung more than Microsoft. But understanding a brand and understanding a stock’s risk-adjusted future returns are entirely different things. The data says familiarity does not predict outperformance — it predicts concentration risk.
What You Miss by Staying in Korea
Average annual returns of major markets from 2010 to 2023:
- KOSPI (Korea): approx. 3.5%
- S&P 500 (US): approx. 12.6%
- MSCI World (global developed markets): approx. 9.8%
- MSCI Emerging Markets: approx. 2.1%
Over the past 13 years, investing only in Korea would have yielded more than 9% less annually compared to investing in the US (Morningstar, 2023). On a 30-million KRW portfolio, that difference compounds to over 300 million KRW difference over 20 years.
Japan’s Lost Decade: The Lesson No One Wants to Learn
The most sobering case study in home bias is Japan. In 1989, the Japanese stock market was the largest in the world — accounting for over 40% of global market cap. Japanese investors who held domestic-only portfolios felt completely safe. Then the Nikkei peaked at 38,957 in December 1989.
It did not recover to that level for 34 years, finally crossing 39,000 again in early 2024. A Japanese investor who held only domestic stocks in 1989 spent three decades flat. Meanwhile, global diversification — holding the entire world market — produced steady long-term gains throughout those same decades (MSCI, 2023).
Korea in 2024 is not Japan in 1989. But the lesson applies universally: no single country’s stock market is guaranteed to outperform the world. The Korean economy is heavily concentrated in a few sectors (semiconductors, shipbuilding, steel) and a few conglomerates. Global diversification hedges against Korea-specific sector risk.
See also: three-fund portfolio strategy
Correlation Data: How Much Protection Does International Provide?
The benefit of diversification depends on correlation — how much two markets move together. Lower correlation = more protection.
| Market Pair | 10-Year Correlation (2013–2023) |
|---|---|
| KOSPI ↔ S&P 500 | 0.71 |
| KOSPI ↔ MSCI Europe | 0.65 |
| KOSPI ↔ MSCI Emerging Markets | 0.78 |
| S&P 500 ↔ MSCI Developed ex-US | 0.85 |
| Stocks ↔ Bonds (BND) | -0.15 |
A correlation of 0.71 between KOSPI and the S&P 500 means they move somewhat together — but not in lockstep. During the 2020 COVID crash, KOSPI fell 35% while US markets fell 34%. During the 2022 rate hike selloff, KOSPI fell 25% while global markets fell 18%. The divergences are real and meaningful over time (MSCI, 2023).
Emerging Markets: Risk, Reward, and the Right Allocation
Emerging markets (MSCI Emerging Markets index: China, India, Brazil, Taiwan, South Korea itself) offer higher long-term growth potential but with significantly higher volatility:
- MSCI EM 10-year average annual return (2013–2023): 2.1% — well below developed markets
- MSCI EM 20-year average annual return (2003–2023): 8.1% — on par with developed markets
- Standard deviation: approximately 22% vs. 15% for MSCI World
Most evidence-based investors recommend limiting emerging market exposure to 5–15% of total equity allocation (Vanguard, 2020). The higher volatility and country-specific risks (China regulatory risk, India political risk, currency volatility) make a large EM overweight inadvisable for most individual investors.
Note: Korea is classified as an emerging market by MSCI (despite being a developed economy by most measures). If you hold MSCI EM ETFs, you are already holding Korean stocks — another reason to diversify globally rather than doubling down on Korea.
See also: index fund guide
Currency Risk Explained — and Why It’s Smaller Than You Think
When you invest in US stocks and the dollar weakens against the Korean won, your returns in KRW terms shrink. This is currency risk. It’s real — but it’s often overstated as a reason to avoid international investing.
Key facts about currency risk for Korean investors:
- It is symmetrical: Currency moves both ways. When the KRW weakens (which happens during global crises — 2008, 2020, 2022), foreign assets in KRW terms actually increase. Foreign stocks act as a natural crisis hedge.
- Hedging costs are expensive: Currency-hedged ETFs typically cost an additional 1–2% annually in hedging costs (Financial Services Commission, 2023). For a 30-year investor, this cost far exceeds the risk of unhedged currency volatility.
- Long-term convergence: Over 20+ year periods, exchange rate effects tend to diminish relative to underlying equity returns. The S&P 500’s 12.6% annual return (in USD) still translates to approximately 10.8% in KRW over the past decade, after currency effects.
The consensus among long-term evidence-based investors: do not hedge currency for equity investments held for 10+ years. The costs outweigh the benefits (Malkiel, 2019).
Implementation: ETFs for Korean Investors
For Korean investors, ETFs are the most efficient way to achieve global diversification.
- US (60%): TIGER US S&P500 or KODEX US S&P500TR
- Global developed markets (20%): TIGER Developed Markets MSCI World
- Emerging markets (10%): TIGER Emerging Markets MSCI
- Bonds (10%): TIGER US Treasury 10-Year
For investors with access to US brokerage accounts, the international options expand significantly:
- VXUS (Vanguard Total International Stock ETF): 8,000+ stocks across 47 countries. Expense ratio 0.07%. The single most efficient way to own all non-US equities.
- IXUS (iShares Core MSCI Total International Stock ETF): Similar coverage to VXUS, expense ratio 0.07%. Useful as a tax-loss harvesting pair with VXUS.
- VEA (Vanguard Developed Markets ETF): Developed markets only (no emerging), expense ratio 0.05%. Lower volatility than VXUS.
The Optimal International Allocation: 30–40%
The evidence points to 30–40% international as the optimal range for Korean investors who already have a domestic life (job, real estate, pension) denominated in KRW:
- Global market cap weight argues for ~40% international (ex-US developed + EM)
- Vanguard’s research suggests 30–40% international optimizes the diversification benefit while managing currency costs (Vanguard, 2020)
- Below 20% international provides limited diversification benefit
- Above 50% international introduces unnecessary currency concentration in a non-KRW direction
For Korean investors, remember your human capital (future salary) is already denominated in KRW and correlated with the Korean economy. Your financial portfolio should deliberately offset this concentration — making the case for 30–40% international even stronger.
See also: tax-efficient investing for Korean investors
Conclusion: Invest in Global Economic Growth
It’s more rational to invest in worldwide economic growth than to bet on a single country. There’s no reason to miss out on the growth of Apple, Microsoft, Google, and Amazon. As a teacher I live and work in Korea, but my investments span the entire world.
Disclaimer: This article is written for investment education purposes. Overseas investing carries currency risk, and past returns do not guarantee future results. All investments carry the risk of capital loss.
Last updated: 2026-03-16
About the Author
Written by the Rational Growth editorial team. Our health and psychology content is informed by peer-reviewed research, clinical guidelines, and real-world experience. We follow strict editorial standards and cite primary sources throughout.
Disclaimer: This article is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with any questions about a medical condition.
Your Next Steps
- Today: Pick one idea from this article and try it before bed tonight.
- This week: Track your results for 5 days — even a simple notes app works.
- Next 30 days: Review what worked, drop what didn’t, and build your personal system.
References
- MSCI. (2023). MSCI Global Market Accessibility Review. MSCI Inc.
- Markowitz, H. (1952). Portfolio selection. Journal of Finance, 7(1), 77-91.
- Morningstar. (2023). Global Market Returns. Morningstar Research.
- Vanguard. (2020). Global equity investing: The benefits of diversification and managing the risks. Vanguard.
- Malkiel, B. G. (2019). A Random Walk Down Wall Street. W. W. Norton.
- Financial Services Commission. (2023). ISA Program Guide. FSC Korea.