The Standard & Poor's 500, often abbreviated as the S&P 500, or just the S&P, is an American stock market index based on the market capitalizations of 500 large companies having common stock listed on the NYSE or NASDAQ. The S&P 500 index components and their weightings are determined by S&P Dow Jones Indices
Call trades that are bought on or above the market's asking price OR put trades that are sold on or less than the market's bid price - expecting a move to the updside.
Put trades that are bought on or above the market's asking price OR call trades that are sold on or less than the market's bid price - expecting a move to the downside.