Account data sharing is the act of a customer allowing their bank or other financial provider to pass information about their account, such as balances, transaction history and account details, to a different company. The receiving firm might be a budgeting app, a lender checking income, or an accounting package. The rules, methods and risks behind this are explained in full in the Financial Data Access entry.
Sharing can happen in two ways. The older method, screen scraping, has the customer hand over their online-banking login so a third party can collect the data itself. The newer method uses dedicated interfaces where the customer gives consent and the bank sends only the agreed data, without the login ever leaving the bank. In the European Union and the UK this is the account information service created by PSD2; in the United States consumer rights to their own data rest on Section 1033 of the Dodd-Frank Act.
Because the data is personal and often sensitive, sharing raises questions of consent, how long access lasts and who is liable if information leaks, which is where it meets data privacy law. Extending the same idea beyond bank accounts to pensions, insurance and investments is called open finance.