Retiring in 4 years: how would you diversify a highly concentrated US portfolio?

**Hello folks,** I’d like to hear general views on long-term portfolio construction for someone approaching retirement in about 4 years. **Quick background:** * Current net worth: around €700k * Current allocation: roughly 95% US large-cap equities, 5% crypto * I keep investing monthly, around €7k per month * I do not plan to sell my current holdings * I am only using new contributions to gradually diversify **What I’m trying to understand:** * How do people think about reducing concentration risk in a portfolio that is heavily tilted toward US large-cap equities? * What types of diversification actually change the risk profile of a portfolio, rather than just adding more lines? * For emerging markets, what are the main arguments for passive exposure versus active management? * Where does gold fit in a long-term equity-heavy portfolio, if at all? * How do you think about China exposure in a long-term allocation, especially given political and regulatory risk? **What I’m not looking to do:** * Add individual stocks * Add small caps * Build a classic MSCI World allocation * Add bonds before retirement * Make a major change to my US exposure I’m mostly interested in different frameworks for thinking about risk, diversification, and portfolio design. **My current thinking is roughly:** * Keep a strong US core * Add some emerging markets exposure * Possibly add a small gold allocation * Possibly include China, or maybe exclude China from the emerging markets sleeve I’m trying to avoid cosmetic diversification and focus on exposures that are actually different from one another. Also, just to be clear, I have a separate cash reserve for short-term needs, so this question is only about invested assets and long-term allocation. Thanks in advance for any perspectives.