This is post is taken from the Frequently Asked Questions.

Yes, most brokerages allow you to buy shares of a bitcoin ETF. Two of the most popular are IBIT (managed by Blackrock) and FBTC (managed by Fidelity). These are not the same as holding bitcoin in cold storage because the bitcoin is held by the custodian and not by yourself. You are able to participate in any movement of the bitcoin price but are not otherwise able to interact with bitcoin besides trading the ETF. 

These are decent alternatives for accounts in which you are not allowed to buy actual bitcoin. They do come with limitations. For one, they are securities and not commodities so if you do a lot of buying and selling, you do have to worry about the wash sale rule. Bitcoin held in self-custody does not need to worry about that rule.

Another limitation is that if you are buying the bitcoin ETF as a store of value and end up needing to access those funds, the ETFs only trade during the hours that the stock market is open. Bitcoin is tradable 24/7.

The bitcoin ETFs also have small fees. Most have expense ratios on the order of 0.25%. That is small but more than the S&P500. VOO has an expense ratios of 0.03% in comparison. Bitcoin held in self-custody has no ongoing fee besides the cost of maintaining and securing your hardware wallet.

Another limitation is for the more paranoid. Bitcoin held in self-custody is not able to be taken away from you while access to the value of bitcoin in an ETF could be halted by the order of a government.

Individual Retirement Accounts (IRAs) that are at brokerages allow you to buy any of the bitcoin ETFs. IRAs do also have the option of being opened at a company like Unchained or Swan IRA where you get to hold real bitcoin, not bitcoin held in an ETF. You can have more than one IRA open at a time.

Some 401ks can be converted into a self-directed 401k. This allows you to invest in things other than the preselected list of mutual funds, like the target date retirement fund that is the default for many programs. If your company allows you to do a self-directed 401k, then you might have the option of buying exposure to bitcoin via the ETFs.