What are the transaction costs associated with equity trading? How are those paid?

For accounts (or a family of accounts) at Fidelity over $1 million, each equity transaction costs $8.00 (up to 3,000 shares). This is one of the lowest institutional trading costs available. The trading cost is essentially a fee paid to the custodian. The transaction fee is debited out of the account at the time of trade and included in the cost basis of the security purchased or sold on a pro rata basis. Accounts that are not custodied at Fidelity may have differing commission structures.