SPX

The highest option OI and volumes for both puts and calls expiring Friday are on 4700.

To play for a possible pin :
BOT 12/20 4700 calls, and sold 4700 calls expiring today (net cost $28) , on 12/15 ($12), and 12/17 ($3.5).

Separately, also rolled the short 4610 call to 12/15 4620, which is part of a diagonal with the Jan 4600 call.