Fidelity data breach exposed the personal information of 77,000 customers

Fidelity Investments suffered a data breach that compromised the personal information of 77,000 customers, the company said Wednesday in a notice to the Maine Attorney General's Office.

The breach occurred in August and is related to two accounts recently opened with the asset management company, the filing said. It's not clear how these accounts gave hackers access to customer data.

Fidelity did not disclose what specific customer data was accessed by the thieves, but said after completing the investigation that no customer accounts or funds were compromised as a result of the breach.

“We discovered this activity on August 19 and took immediate action to disable access,” Fidelity said in a notification letter to clients.

Fidelity declined to comment further on the breach, but told CNET in an email that the company has resources to assist customers with questions about the attack.

“Fidelity takes seriously its responsibility to serve customers and protect information,” the company said.

Read more: Data breach exposes Social Security numbers of 237,000 Comcast customers

What to do if you are caught in the Fidelity breach?

Fidelity's data breach affected a small percentage of the company's 51.5 million customers. If you are affected, Fidelity offers 24 months of credit monitoring and identity theft protection services from TransUnion Interactive. To activate this offer, use the code you received in your letter via USPS mail. Identity theft protection can help notify you of data breaches in advance and alert you if your personal information has been found on the dark web.

In addition to using this free service, you should change your password and monitor your Fidelity account for suspicious activity. If you have a Fidelity account and aren't sure if you've been affected, it's always a good idea to change your password. Regularly updating your password can make it harder for criminals to break into your account. A password manager can make this process much easier.

Depending on what sensitive data you have accessed, you should also monitor your credit reports with TransUnion, Equifax, and Experian.

You can even choose to place a fraud alert on your credit score or freeze your credit with each of the three credit bureaus so that no one can open new credit accounts – such as car loans or credit cards – in your name.

Protect your personal information and gain peace of mind with CNET's top picks for identity theft software.