Open Interest quantity shows the total number of active contracts in each strike price and expiration date. Open interest is one of the columns displayed in an option pricing chain along with the current contract price, price change, bid price, ask price, and volume. Open interest shows the current total number of option contracts that exist in the options market. This describes the option contracts that are being traded and haven’t been closed by an offset trade, option exercise, or assignment. When an option trader buys or sells an option contract, the trade is entered on the market as an opening or a closing option transaction. If you buy new call options that must be written then you are buying the calls to open. That purchase would add to the open interest after they are written. After the position is sold those options would close if they are bought back which would cause open interest to fall. When an option is sold to open it can also add more contracts to open...