Four months ago, China decided to devalue the Yuan sending a shudder up and down collateral chains globally and forcing carry trade unwinds and derisking everywhere. Friday August 21st saw notable weakness as that weakness washed ashore in US equities.. and then Black Monday struck. The ensuing debacle stalled The Fed and shocked markets.

The last week, we have seen China devalue the Yuan very significantly, EM capital markets turmoiling, and today, that was ashore in US equities… what happens next?

Deja vu?

Deja vu?

As a reminder, JPMorgan’s “seer” Marko Kolanovic warned this week that…

“As for near-term risks—we believe the most imminent market catalyst will be the December Fed meeting in which we are likely to see the first rate hike of the cycle.“

But to a market which has traded mostly on technicals and program buying (and selling) in recent months, there is something far more troubling than just what the Fed will announce:

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.