JPM Head Quant warns of the following surrounding December 16th FOMC:
This important event falls at a peculiar time—less than 48 hours before the largest option expiry in many years. There are $1.1 trillion of S&P 500 options expiring on Friday morning. $670Bn of these are puts, of which $215Bn are struck relatively close below the market level, between 1900 and 2050. Clients are net long these puts and will likely hold onto them through the event and until expiry. At the time of the Fed announcement, these put options will essentially look like a massive stop loss order under the market.
What does this mean? Considering that the bulk of the puts have been layered by the program traders themselves, including CTA trend-followers, and since the vol surface of the market will be well-known to everyone in advance, there is a very high probability the implied “stop loss” level will be triggered, and the market could trade to a level equivalent to the strike price, somewhere in the 1,800 area, or nearly 200 points below current levels.