How advisors use covered calls to cut concentrated stock risk

Financial advisors are increasingly recommending covered-call strategies for clients who hold large positions in a single stock. They use option premiums as a source of cash to buy diversified securities or ETFs, to help cover capital gains taxes and to reduce company-specific, or idiosyncratic, risk while keeping downside exposure in place.

Research by Edwin J. Elton and Martin J. Gruber found that shifting from a single-stock portfolio to a diversified basket of about 20 names can lower expected portfolio risk from roughly 47% to under 9% by removing much of the idiosyncratic risk. Historical returns for large S&P 500 companies illustrate the variation in single-stock outcomes: from 2005 to the present, Exxon Mobil returned about 13.3% annualized, Citi returned about −5.6% and the S&P 500 averaged roughly 17% per year.

A covered call involves selling a call option on shares the investor already owns and receiving an option premium. The option buyer gains the right to buy the shares at a set strike price before expiration. If the stock rises above that strike, the shares can be called away and any gain above the strike plus premium is forfeited. If the stock falls, the owner still suffers the loss, reduced only by the premium received.

Advisors typically reinvest premiums into diversified holdings on a scheduled basis, creating a dollar-cost-averaging path away from concentration. Firms that use the approach generally treat it as a multi-year transition tool, often spanning 10 to 15 years or longer, with option income helping to smooth portfolio volatility during the process.

Strike selection controls how quickly a concentrated position is reduced. Writing calls with strikes near the market price generates higher premiums but increases the chance of assignment and the likelihood of realizing capital gains sooner. Choosing strikes further out generates lower premium income, preserves more upside and lowers the probability of assignment, which supports a slower transition.

Practical and tax considerations affect the choice to use covered calls. Many concentrated positions have low cost bases, so selling shares can trigger substantial capital-gains taxes. Option income can be earmarked to pay those taxes or used alongside a planned sale schedule. Options can be exercised at any time before expiration, creating an unexpected sale and tax event. Closing an option position to avoid assignment reduces net premium and may require cash to complete the transaction.

Other constraints include transaction costs, the need for active monitoring of options positions, and underperformance versus an uncovered stock in rapidly rising markets because upside is capped. The tax treatment of option premiums can differ from long-term capital gains, and options trading is not suitable for all investors. Some ETFs and funds use covered-call strategies and carry the same trade-offs: limited upside above the strike and exposure to declines in the underlying securities.

Some asset managers offer model or custom portfolios that combine diversified exposures with covered-call overlays to manage staged exits from concentrated holdings. Managing concentrated positions with options typically requires ongoing oversight and a plan that addresses tax timing, reinvestment rules and monitoring of assignment risk.

Diversification reduces company-specific risk but does not eliminate the risk of loss. Investors and advisors weigh the trade-offs among income, tax timing, upside participation and assignment risk when considering covered calls as one tool among several for addressing concentrated stock positions.