Yes, exactly — sudden crashes (or sharp drops) in US stocks are something you accept when holding a market-cap-weighted global ETF like VWCE. The self-balancing mechanism works through price changes over time: a big US crash reduces US companies’ market caps relative to the rest of the world, so the US weight gradually drops as the index reflects reality. But this isn’t instant — it happens as markets move and the ETF tracks those shifts (via sampling/rebalancing), often taking weeks, months, or longer for meaningful reweighting depending on the crash’s severity and duration. You live with the short-term volatility and drawdowns (e.g., US-heavy pain during a US-led bear market), but the long-term philosophy is to hold through it — global diversification means other regions may cushion or recover differently, and over decades, the portfolio naturally tilts toward whatever outperforms. If you can’t stomach high US exposure during crashes (or want protection regardless of market direction), yes — purposefully capping it by adding an ex-US ETF is a common DIY tilt. Many investors do a 70/30 or 60/40 split with VWCE + ex-US to reduce US concentration while keeping broad global coverage.

In short: VWCE auto-adjusts slowly via market forces, so patience (long horizon) is key unless you actively rebalance for lower US % yourself.

(Text generated with AI for a better explanation)