This Citibank report is quite interesting. With 5% in gold as a foundation, plus some Bitcoin, the traditional 60/40 portfolio can actually be more stable and more profitable, unafraid of both bull and bear markets in bonds.

Citigroup states that including gold and Bitcoin in a traditional 60/40 stock and bond portfolio can enhance long-term efficiency. Allocating about 5% to gold alone has significantly improved performance; if distributed between gold and Bitcoin, returns are higher and risk does not increase substantially. This combination outperforms the 60/40 during bond market strength and also performs better in bear markets. During geopolitical conflicts and market volatility, Bitcoin sometimes outperforms gold when the bond market is weak; in the past two months, Bitcoin has risen about 9%, while spot gold has fallen about 4%.