Covered Call Overwriting
Covered call overwriting means selling call options against stock you already own, collecting premium income in exchange for capping how much of a rally you get to keep.
Prerequisites: The Option Greeks
An investor who already owns a stock and doesn't expect a huge rally soon can sell someone else the right to buy that stock at a higher price, and pocket the premium for doing so. That's a covered call: "covered" because the shares are already owned, so if the option is exercised, the stock is simply delivered — no need to buy it in the market at a possibly much higher price the way an uncovered ("naked") call seller would have to. In exchange for that premium income, the seller gives up any stock gains above the strike price; if the stock rockets past the strike, the buyer of the call captures that excess, not the shareholder.
The trade-off in one example
An investor holds 100 shares of a stock trading at $50 and sells one call option struck at $55, collecting a $2 premium per share ($200 total). Three outcomes at expiry: if the stock stays at $50 or falls, the call expires worthless and the investor keeps the full $200 premium on top of the stock position, which softened the blow of any decline by exactly that $200. If the stock rises to $55, the call still expires worthless (right at the strike), and the investor again keeps the $200 plus the full $5-per-share gain on the stock. If the stock rises to $65, the call is exercised: the investor must deliver shares at $55, missing out on $10 per share of further gain, but still nets the $5-per-share gain up to the strike plus the $2 premium — $7 per share total, versus $15 per share for someone who simply held the stock uncovered. The premium is compensation for capping the upside, not free money.
What this means in practice
Covered call overwriting is a common income strategy for investors holding a large, relatively stable stock position who are willing to trade away tail upside for a steadier stream of premium income, and it's the basis for popular buy-write index products that systematically sell calls against a broad equity index every month. It performs best in flat or mildly rising markets and worst in sharply rising ones, since a big rally is exactly the scenario where the capped upside costs the most relative to simply holding the stock.
Selling a covered call does not protect against the stock falling sharply — the premium collected offsets only a small, fixed slice of any decline, and a shareholder who sells calls repeatedly against a stock that keeps dropping can end up having given away upside during earlier rallies while still absorbing nearly the full loss on the way down. "Covered" describes the call's risk, not the stock position's downside risk.
Covered call overwriting trades a capped upside for premium income today — it works well when the stock stays flat or rises modestly, and it costs the most, in opportunity terms, exactly when the stock rallies hard past the strike.
Practice
- Using the numbers above, what's the maximum possible profit per share on the covered call position, and at what stock price is that maximum first reached?
- If the same investor instead sold a call struck at $60 instead of $55, would the premium collected likely be higher or lower, and why?
Related concepts
Practice in interviews
Further reading
- McMillan, Options as a Strategic Investment (Ch. 3)