Definition of 'Primary Instrument'
A financial investment whose price is based directly on its market value. Examples of primary instruments include stocks, bonds, certificates of deposit, bills and anything else that has its own value. By contrast, the price of derivative instruments, such as options, swaps and futures, is based on the value of their underlying assets.
Investopedia explains 'Primary Instrument'
While the markets have established hundreds of instruments to facilitate the flow of capital and the management of risk, primary investments like stocks are what most beginning investors think of when they think about investing. This is because investing in primary instruments requires only basic knowledge of markets and investment principles.
A non-primary instrument would be something like a call option, which gives the owner the right to purchase the underlying stock at a certain price. So, if the price of the stock goes up, the call option's value also goes up. The call's value is based on the value of something else so it is not a primary instrument.