Quantitative easing is an economic monetary policy intended to lower interest rates and increase money supply. It saw an increase in profile and use after the 2008 financial crash and subsequent recession.
The price at which an asset was last traded, or the price at which it can currently be bought or sold.
Quadruple witching refers to an expiration date that includes stock index futures, stock index options, stock options and single stock futures. All four asset classes expire simultaneously on the third Friday of March, June, September and December.