After days of saying he wouldn\'t, the chairman of the Swiss National Bank resigned abruptly on Monday. Philipp Hildebrand was brought low by a swirling controversy over foreign exchange transactions that made tens of thousands of dollars for him and his wife. Hilde-brand said he could not prove he had been unaware of a currency trade made by his wife and wanted to protect the integrity of the central bank. Swiss central bank chief Philipp Hildebrand has quit his post, despite vowing to stay just days ago, in the face of growing criticism over a controversial currency trade made by his wife. Philipp Hildebrand said: \"Conscious as I am of the challenges currently facing our country and given my responsibility for my office and for the SNB as an institution, I have therefore decided to relinquish my post with immediate effect\". Hildebrand’s wife Kashya - a former trader who now runs a Zurich art gallery - bought 400,000 Swiss Francs worth of dollars from Sarasin Bank three weeks before her husband oversaw steps to cap the rise of the franc. A former bank employee was accused of leaking the data. He’s now reported to be receiving psychiatric help after attempting suicide. Phillipp Hildebrand stepped down just hours after senior Swiss National Bank officials arrived to question him about the transaction. Philipp Hildebrand said: \"I have come to the conclusion that is not possible to provide conclusive and final evidence that my wife did indeed initiate the foreign exchange transaction on the 15th of August without my knowledge. The fact is my word is my bond, I had no knowledge of my wife’s transaction on that day. Unfortunately mistakes were made in connection with these transactions, I detailed these on Thursday and I apologized for them. I deeply regret these mistakes as well as the entire situation\". The scandal has raised questions about transparency at the central bank. It initially failed to publish its internal ethics codes saying auditors had found no misuse of prigged information. The Swiss parliament will now consider whether the National Bank should tighten its rules. The Swiss franc rose after Hildebrand’s resignation.