SPY is the closest thing to owning "the US market itself." Spread across roughly 500 names, single-stock risk is low, and low fees plus a massive asset base make it one of the most liquid ETFs available. It's a reasonable first US ETF for Korean investors, though it's worth remembering that tech now makes up over 30% of the fund — this isn't full diversification.

Like every US-listed ETF, SPY carries no currency hedge. When the won is trading at a historically weak level against the dollar, phasing in purchases over time rather than deploying a lump sum can help manage your average entry rate.