The Swiss central bank may need to ready its “nuclear weapon” of buying euros as the franc headed for the biggest weekly advance on record. While the Swiss National Bank has so far avoided currency purchases in its latest bid to keep a lid on the franc, it may soon have no alternative but to follow through on its threat to intervene, economists and strategists said. “The SNB will fire its nuclear weapon and start interventions if the franc reaches parity,” said You-Na Park, a strategist at Commerzbank AG in Frankfurt. “The current franc levels really hurt the economy.” The SNB, led by Philipp Hildebrand, is under ... (full story)