The Swiss National Bank (SNB) took the step of publishing the document following a slew of media reports about currency trading by the chairman and his partner Kashya.
Hildebrand will himself talk publicly about the affair on Thursday, the SNB said in a statement, saying that some reports were partly incorrect.
The Swiss government meanwhile expressed its confidence in the bank chief.
“From the emails available to us, it appears that Philipp Hildebrand was not aware of the transaction,” said a report by PricewaterhouseCoopers of the purchase of $504,000 for 400,000 Swiss francs on August 15th.
Hildebrand instructed his bank, Banque Sarasin in Basel, to only act on his instruction in the future, it said.
In a news report to be published on Thursday, Swiss weekly newspaper Weltwoche calls Hildebrand a “speculator” who benefited from several dollar and euro transactions on the foreign exchange market between March and October last year.
The SNB says the couple’s transactions did not flout central bank rules and it published a copy of the regulations on Wednesday along with the auditors’ report.
Switzerland’s Federal Council said on Thursday it had “full confidence” in Hildebrand after an audit carried out by the Federal Audit Office also found no evidence of foul play.
“The audit revealed no indication of any transactions in which inside knowledge of confidential facts had been used or which were contrary to the rules of the SNB,” said a statement.
“The Federal Council has no reason to question the validity of the audit findings and has expressed its full confidence in Mr Hildebrand.”
The probe was reportedly launched after SVP figurehead Christoph Blocher went to then president Micheline Calmy-Rey with extracts of banking documents.
Blocher, a critic of SNB policy under Hildebrand, has so far remained silent on the matter.
Banque Sarasin in Basel said that one of its employees had admitted illegally transmitting banking details to a lawyer close to the SVP.
In a further claim Weltwoche said the same employee had lodged a complaint against Hildebrand for alleged insider trading.
The SNB on September 6th imposed a bottom limit for the franc against the euro to stop the currency soaring and biting into Swiss exporters’ earnings.
The action saw both the euro and the dollar rise against the franc.
Three weeks earlier Kashya Hildebrand, who runs an art gallery in Zurich, said she bought dollars due to the fact that they had “hit a very low level and become ridiculously cheap.”
In a written statement to SF Swiss television, Hildebrand said she had always followed the exchange market and had worked in the banking sector for 15 years between 1984 and 1999 before moving into art.
On August 15th the dollar was worth 0.79 francs compared to 0.92 on October 4th.
According to Weltwoche, Hildebrand made 75,000 francs ($80,500) on the purchase and sale of $500,000 between these dates.