double-witching
n.— «One factor in the day’s buying may be related to Friday’s “double-witching” session, Wall Street’s term for the session when stock index options and stock futures contracts expire on the same day. This often results in additional, and sometimes volatile, tradin» —“Dow shrugs off bad news to post triple-digit gain” by Tom Walker Atlanta Journal-Constitution (Ga.) Aug. 19, 2004. (source: Double-Tongued Dictionary)