The Securities and Exchange Commission and New York Stock Exchange reportedly are looking into allegations that employees at fund manager Fidelity's brokerage unit might have altered records prior to internal audits.

Several Fidelity employees have already been fired as a result of the probe, The Wall Street Journal said. Fidelity is privately held but is subject to record-keeping standards that apply to broker dealers.

Regulators are probing into whether managers tried to deceive internal auditors by altering customer records, and are also probing whether those managers might have had as a motive some kind of financial reward for a "perfect audit," the newspaper said, citing people familiar with the situation.

A Fidelity spokeswoman said: "Last year, we identified issues relating to documentation at certain investor centers. We took immediate action to correct the problem and brought it to the attention of our regulators, and we have been working with regulators on these issues." She added: "These document issues had no financial impact on customers, and there was no customer harm," according to the Journal.