A study by Citi has found that adding bitcoin and gold to a portfolio significantly increases the efficiency of a bond-and-equity portfolio over the last decade. The study suggests that holding some of these assets in small amounts could increase portfolio efficiency. However, the study also noted that bitcoin's price action tends to move in tandem with other risk assets rather than as a hedge. Citi's findings suggest that when bond markets are weak or unstable, bitcoin performs better than gold.