Derivatives are financial instruments whose value is based on an underlying asset. They include forwards, futures, options, and swaps. Forwards involve an agreement to buy or sell an asset at a set price on a future date. Futures are similar to forwards but trade on an exchange and are marked to market daily. Options give the right but not obligation to buy or sell an asset at a strike price. Swaps allow parties to exchange interest or currency payments over time to hedge risks. Common derivatives are mortgage-backed securities which pool home loans and student loan instruments. Derivatives make up the largest part of the total financial market.