Hildebrand has yet to comment on the case, which first became public when the SNB issued an unprompted statement Dec. 23 declaring that "rumours" of wrongdoing by its 48-year-old chief were unfounded and its rules against insider trading weren't breached.
An Swiss central bank spokeswoman, Silvia Oppliger, decline to comment Wednesday on the latest report.
The Zurich-based Weltwoche weekly said it has obtained bank statements showing that Hildebrand himself bought large amounts of U.S. dollars before selling them for profit after his central bank depressed the value of the Swiss franc.
"We have all the bank statements showing the relevant transactions, plus a verbal assurance from a bank employee confirming that it was Hildebrand personally, not his wife, who ordered the transactions," Weltwoche's Deputy Editor-in-Chief Philipp Gut told The Associated Press in a telephone interview.
Gut declined to identify the bank employee, but said he was a client adviser at Bank Sarasin. The Basel-based private bank said it has fired an IT support employee who leaked confidential information about "currency transactions by the family of the president of the Swiss National Bank."
Gut said he didn't known if the fired employee and the Weltwoche source were the same person.
According to Weltwoche, Hildebrand made several large dollar transactions between March and October last year.
The magazine claims Hildebrand bought over half a million U.S. dollars in two transactions on Aug. 15, 2011, three weeks before the SNB set the minimum exchange rate of the euro at 1.20 francs. The move caused the value of the franc to instantly drop about 8 per cent against other major currencies, including the dollar.
Three weeks after the SNB set the exchange rate floor on Sept. 6, Hildebrand sold his dollar holdings for a profit of 75,000 Swiss francs ($83,000), Weltwoche reported.
"It's a classic forex speculation," said Gut. "The only option for Mr. Hildebrand is to step down."
The Swiss National Bank said last month that Hildebrand's wife Kashya, a former currency trader who now runs an art gallery in Zurich, bought an unspecified amount of U.S. dollars for herself and her daughter. The central bank declined to say whether she sold them for a profit, but declared that the bank's board concluded Dec. 22 there had been no inappropriate transactions nor any abuse of privileged information.
Weltwoche is considered close to the nationalist Swiss People's Party and its prominent billionaire backer, former Justice Minister Christoph Blocher.
Bank Sarasin said in a statement late Tuesday the fired IT support specialist passed details of the Hildebrands' account to a People's Party lawyer, who then met with Blocher.
Blocher, who has repeatedly criticized Hildebrand's management of the central bank, said through his spokesman he had no plans to comment on the Hildebrand case.