A simple, long-term mix: 90% SPY (US stocks) and 10% GLD (gold), with automatic yearly rebalancing to maintain the 90/10 target for growth with diversification.

What this strategy does in plain language: 1) SPY is a fund that mirrors a broad basket of large US companies; GLD is a fund that tracks gold. 2) You start with 90% of your money in SPY and 10% in GLD. For example, with $100 total, about $90 goes to SPY and $10 to GLD. 3) Your target is 90% SPY and 10% GLD. Each year, you check the actual mix. If SPY has grown and now represents more than 90% of the total, you buy GLD (or sell SPY) to bring the mix back to 90/10. If GLD has grown, you do the opposite. 4) Rebalancing happens once a year to keep costs low and reduce decision-making fatigue. 5) The aim is to grow your money mainly from stocks while using a small gold position to diversify and potentially reduce some risk during market stress. 6) Possible downsides: you may miss out on bigger gains if gold rallies strongly or you may see bigger drawdowns during stock crashes; fees and taxes of ETFs apply and can eat into returns.

Beats SPY out-of-sample: ~19.8% annualized return vs ~17.9%; higher risk-adjusted return (Sharpe ~1.27 vs ~1.08); lower max drawdown (~16.6% vs ~18.8%); simple 90/10 SPY/GLD with annual rebalancing for diversification.