Strike Price is the price at which an option can be exercised to buy or sell the underlying stock  or futures contract.

S&P 500 Index (Standard and Poor’s 500 Index) is a composite of the 500 most actively traded public companies in all ten economic sectors of the U.S. It is maintained by Standard and Poor’s, a division of the Parent company McGraw-Hill.

Selling Short is a trade in which the investor borrows a security and sells it to another investor in the market. To close the short position an investor has to cover (purchase the same security from the market) and return it to the person they borrowed it from.

Security

Security is any financial instrument that represents a financial value