Swiss weekly newspaper Weltwoche said in a statement ahead of its Thursday publication that it was Hildebrand himself, and not his wife, who was behind the purchase and selling of currency that sparked a probe by the Swiss National Bank (SNB).
The bank chairman also made several other dollar and euro transactions on the foreign exchange market between March and October last year, according to Weltwoche, a publication close to the far-right Swiss People's Party (SVP).
In March alone, Hildebrand bought dollars worth $1.1 million Swiss francs, the paper claimed, saying it had had access to extracts from the Hildebrands' banking documents.
Contacted by AFP on Wednesday, the SNB gave no comment on the new revelations.
The central bank said in December that an independent investigation into the Hildebrand couple's transactions had found no evidence of foul play.
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 in a statement late Tuesday however 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.