How about quadruple witching - stock index futures, stock index options, stock options, and single stock futures -Quote from danjos:
Is this Friday an option expiration week? Is it triple withching?
Can anybody tell me where I can find info about the expiration date?
Quote from NYSEProTrader:
How about quadruple witching - stock index futures, stock index options, stock options, and single stock futures.
Quadruple witching: 3rd Friday of March, June, September and December.
http://online.barrons.com/public/page/barrons_econoday.html