Swiss Central Bank Chief Tenders Surprise Resignation Pascal Lauener/Reuters The chairman of the Swiss National Bank, Philipp M. Hildebrand, resigned on Monday. FRANKFURT - The head of the Swiss central bank, who has been under fire for personal currency trades he and his wife made last year, will resign effective immediately, the bank said Monday. The resignation of Philipp M. Hildebrand came as a surprise. Just last week, he offered a detailed defense of his conduct and appeared to have the support of the council that oversees the Swiss National Bank. An internationally known advocate of stricter bank regulation, Mr. Hildebrand faced accusations that he or his wife bought and sold large amounts of dollars last year at the same time that the S.N.B. was intervening in currency markets. The bank said Mr. Hildebrand, a 48-year-old former manager at a New York hedge fund, would make a statement about his resignation later Monday in Zurich. The accusations came to light after a former information technology worker at Bank Sarasin, a Swiss private bank, gave information from Mr. Hildebrand's personal account to the right-wing Swiss People's Party. The party, which has substantial popular support, has been sharply critical of the monetary policy pursued by Mr. Hildebrand, as well as his efforts to constrain risk-taking by Swiss banks. The Bank Sarasin employee, who has not been identified, faces criminal charges for violating bank secrecy laws. The 39-year-old man is in a psychiatric clinic after attempting suicide, the Sonntagszeitung and other Swiss media reported.