A collar can be established by holding shares of an underlying stock, purchasing a protective put and writing a covered call on that stock. The option portions of this strategy are referred to as a combination. Generally, the put and the call are both out-of-the-money when this combination is established, and have the same expiration month. Both the buy and the sell sides of this spread are opening transactions, and are always the same number of contracts. In other words, one collar equals one long put and one written call along with owning 100 shares of the underlying stock. The primary concern in employing a collar is protection of profits accrued from underlying shares rather than increasing returns on the upside.

An investor will employ this strategy after accruing unrealized profits from the underlying shares, and wants to protect these gains with the purchase of a protective put. At the same time, the investor is willing to sell his stock at a price higher than current market price so an out-of-the-money call contract is written, covered in this case by the underlying stock.

This strategy offers the stock protection of a put. However, in return for accepting a limited upside profit potential on his underlying shares (to the call's strike price), the investor writes a call contract. Because the premium received from writing the call can offset the cost of the put, the investor is obtaining downside put protection at a smaller net cost than the cost of the put alone. In some cases, depending on the strike prices and the expiration month chosen, the premium received from writing the call will be more than the cost of the put. In other words, the combination can sometimes be established for a net credit - the investor receives cash for establishing the position. The investor keeps the cash credit, regardless of the price of the underlying stock when the options expire. Until the investor either exercises his put and sells the underlying stock, or is assigned an exercise notice on the written call and is obligated to sell his stock, all rights of stock ownership are retained.