According to BlackRock (NYSE: BLK), the $11.5 trillion asset management firm behind the most popular spot Bitcoin ETF (the iShares Bitcoin Trust), the optimal allocation for most investors is still just 2%. BlackRock started by considering a typical 60/40 portfolio (60% stocks, 40% bonds). It then modeled the impact of adding progressively higher amounts of Bitcoin to that portfolio, to see how it changed its overall risk-reward profile.