State Regulators Widen Libor Investigation

State regulators are widening their investigation into interest rate manipulation, pursuing wrongdoing at seven of the world’s biggest banks.

The New York State attorney general, Eric T. Schneiderman, subpoenaed several banks last month, including JPMorgan Chase, Deutsche Bank and the Royal Bank of Scotland, a person briefed on the matter said. The requests for information follow Mr. Schneiderman’s decision this year to open inquires into Citigroup and UBS, said this person, who spoke on condition of anonymity.

HSBC and Barclays, the British bank that recently settled rate-rigging accusations with federal authorities, have also received subpoenas from Mr. Schneiderman.

The New York regulator’s push to ramp up his investigation reflects the broader escalation of the rate-rigging case. The Connecticut attorney general, George Jepsen, has joined the New York investigation, while state attorneys general in Massachusetts and Maryland have opened their own inquiries.

The state scrutiny comes on top of a wide-ranging federal investigation, involving regulators and the Justice Department, as well as several examinations from authorities overseas. Some traders at banks around the world are also facing potential criminal charges.

The case centers on how banks set a benchmark rate, the London interbank offered rate, or Libor, which affects the cost of trillions of dollars in mortgages and other loans. In June, Barclays agreed to pay $450 million for reporting false rates to bolster its profits and project a rosy image of its health.

Spokeswomen for the attorneys general in New York and Connecticut declined to comment. News of the subpoenas was first reported by Bloomberg News.