Bitwise CIO Matt Hougan suggests that Bitcoin ETF holders should consider diversifying their portfolio with Ethereum, given the potential for spot Ethereum ETFs in the US. Hougan cites three reasons for this.

Firstly, diversification can provide investors with a safety net if one asset falls out of favor. Currently, Bitcoin's market cap accounts for 55% of the entire crypto market, with Ethereum comprising 18.6%.

Secondly, the fundamentally different nature of Bitcoin and Ethereum makes it difficult to choose between them. Bitcoin is optimized towards being "better money," while Ethereum is designed for "programmable money" enabling blockchain applications like stablecoins and DeFi.

Lastly, historical performance shows that both assets work best when balanced together in a portfolio. A portfolio with a 70/30 split between BTC and ETH had a higher cumulative return over the past four years than a portfolio purely allocated to BTC.

However, Hougan acknowledges that Bitcoin's existing lead and community orientation towards being a dominant form of "money" in crypto could be a reason for investors to remain BTC only.