Open interest for VIX calls reaches highest level in 5 yearsParallels with 2011 spur hedging for extreme selloffIn Washington debt-ceiling brinkmanship is threatening to push the US into default. And on Wall Street, traders are gaming out what could be a rare Black Swan event.In the options market, hedges against a volatility breakout are seeing the most demand in five years. The cost to protect against a market selloff of around 10%, or one-standard deviation, is the highest in a year. Demand for tail-risk hedges that pay out in a fall as precipitous as 30%, or three deviations — a Black Swan event — has risen to levels last seen at the peak of March’s banking turmoil.The doomsday hedging is taking place on the market fringes, against a pervasive calm that’s pushed the widely used Cboe Vo