Crypto exchange-traded fund (ETF) issuer Fidelity Investments confirmed a data breach compromised the personal information of over 77,000 customers.

On Oct. 9, Fidelity notified Maine’s attorney general that 77,099 of its customers were impacted by a breach — a fraction of its 51.5 million customer base.

An attacker accessed customer names and other personal identifiers between Aug. 17 and 19 by using two recently established customer accounts.

The unauthorized access was terminated on Aug. 19 when Fidelity spotted the breach.

The $5 trillion asset manager said it had received assistance from “external security experts” to resolve the matter.

The company stressed that no Fidelity accounts were accessed.

Excerpt from Fidelity’s “Notice of Data Breach” sample letter sent to 77,000 customers. Source: Maine attorney general

Fidelity said it’s offering a free credit monitoring and identity restoration service to those impacted for two years “to detect any unusual activity that may affect your personal financial situation.”

Those impacted will need to enroll with credit reporting company TransUnion Interactive.

“[It is also] a good idea to remain vigilant for fraudulent activity or identity theft by regularly reviewing your statements,” Fidelity added.

It’s Fidelity’s fourth data breach over the last 12 months, with the others occurring on March 4, March 18 and July 19.

Fidelity did not immediately respond to a request for comment.

Related: OpenAI’s press account hack was 5th security breach in 20 months

Fidelity is one of several asset managers to launch spot Bitcoin ( BTC ) and Ether ( ETH ) ETFs in the United States this year.

The Fidelity Wise Origin Bitcoin Fund (FBTC) has tallied nearly $10 billion in flows since launching on Jan. 11, while the Fidelity Ethereum Fund (FETH) has taken in $445 million in flows since July 23.

ChatGPT creator OpenAI and telecommunications services firm AT&T have also suffered data breaches this year, with more than 100 million customers affected in the AT&T case.

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