A protective put, sometimes called a 'married put', is a portfolio insurance strategy where you buy a put option against shares you already own. It establishes a floor below which your losses cannot exceed—no matter how far the stock falls, your losses are capped at the strike price of the put minus the premium paid, with respect to your cost basis.
This strategy is ideal when you hold shares with large unrealized gains and want to protect those gains without triggering a taxable sale event. The put acts as insurance: if the stock declines sharply, the put increases in value, offsetting the stock's loss. If the stock continues to rise, the put expires worthless—a cost you pay for the peace of mind of having defined the worst-case outcome.
The total cost of the protective put includes the premium paid, which represents your insurance expense. This cost directly reduces the net return on your stock position. If the stock stays flat or rises modestly, you will have 'wasted' the premium, similar to paying for car insurance that you never use. The trade-off is that you avoid catastrophic losses in tail-risk scenarios.
The choice of put strike balances protection level against cost. An ATM put provides immediate dollar-for-dollar protection but is the most expensive. A 10% OTM put is much cheaper but only provides protection after a 10% decline. Many investors use a 'rolling deductible' approach—buying 5-10% OTM puts quarterly, accepting that first tranche of loss in exchange for significantly lower insurance costs over time.
Protective puts are not permanent solutions—they expire. Investors who use them for long-term protection must roll them regularly, paying ongoing premium costs. For persistent long-term hedging needs, collars (simultaneously selling a call to finance the put purchase) can significantly reduce or eliminate the net cost of the protection.