It's an SEC rule rule 209 if I'm not mistaken. If a stock is down 10% or more in a session, it cannot be shorted. This applies to all stocks/ETFs/ETNs. It will reset tomorrow, and you can short away if you want. I can't ever get shares to short anyway. Just short VXX if you really want to go short, although I don't think this is the time to go short. We need a correction before the next leg up.
It’s been a tough session for traders who are betting directionally on more stock-market volatility.
The latest sign: ProShares Ultra VIX Short-Term Futures ETF (UVXY). is down by nearly 11% on the session. A few minutes after the Fed’s latest statement, NYSE Arca enacted a short-sale restriction on this leveraged volatility trading fund.
UVXY, barely known to most investors, has quickly become one of the most heavily traded ETFs in the entire market.