Are there any minimum balance requirements for crypto portfolios?

There are no minimum balance requirements for crypto portfolios. This means that the minimum balance is $0. 

One condition to note is that the smallest deposit amount you can make into a crypto portfolio is $10. This is due to ACH transaction limitations. 

All crypto portfolios contain a cash allocation and the number of coins in your portfolio is reduced at a low account balance. See portfolio disclosures for more detail.