Treasury Bills Beside a Call Can Preserve Less Than the Starting Capital

A fictional investor starts with $10,000, spends $9,215 on Treasury bills and uses the remaining $785 to buy a call and pay its opening costs. Most of the money sits in government securities. The portfolio can nevertheless finish with $9,500 when the call expires without value.

The missing $500 comes from the initial budget. The bill's $285 maturity gain offsets only part of the $780 call premium and $5 opening charge. A Treasury's scheduled face-value payment applies to the bills purchased. It does not reimburse the separate option expense.

For someone considering a bill-and-call arrangement, the useful first calculation is the minimum modeled ending amount after the option can lose its premium. Describing most of the assets as Treasury bills cannot supply that number.

Separate the bill's payment from the call's payoff

TreasuryDirect explains that Treasury bills are sold at a discount or at face value and pay face value at maturity. Purchase cost and face amount are different entries in the budget.

A purchased call adds a contingent payoff. The Options Industry Council's long-call guide explains that a call can expire without value, losing the premium paid. Its value also depends on price movement occurring within the contract's life.

Settlement terms matter. Cboe's XSP overview describes cash settlement and exercise only at expiration, while its specifications list a $100 multiplier. Those are examples of real contract features. The following calculation uses an invented index and invented prices, not an XSP quotation or an available trade.

Reconcile a fictional $10,000 budget

Assume a single 26-week period, all amounts in U.S. dollars, and no borrowing. Treasury bills with a $9,500 face amount cost an assumed $97 for each $100 of face value: $9,500 multiplied by 0.97 equals $9,215. The bills are held to maturity and pay the stated face amount.

The same account buys one fictional European-style, cash-settled index call with a 100-point strike and a $100 multiplier. An assumed execution premium of 7.80 points costs $780. Opening broker and exchange charges total a fictional $5. The account therefore spends exactly $9,215 + $780 + $5 = $10,000.

The model assumes the bill's payment and any option cash settlement have both arrived by the comparison date. It assumes zero bill transaction charges, zero option exercise or settlement charges, and no other account fees. Actual calendars, account access and charges require separate checks. Taxes, inflation and currency changes are excluded. None of these invented prices is a current yield, forecast or suggested allocation.

Let the option's final exercise-settlement value be I. Its cash payoff is max(I - 100, 0) x $100. The portfolio's ending amount is the $9,500 bill payment plus that payoff.

Three outcomes show where the original capital stands:

• At a settlement value of 80 points, the call pays zero. The portfolio ends at $9,500, a $500 loss, or 5% of the starting amount.
• At 105 points, the call pays (105 - 100) x $100 = $500. The portfolio ends at $10,000, equal to its starting amount under the stated cost assumptions.
• At 120 points, the call pays (120 - 100) x $100 = $2,000. The portfolio ends at $11,500, a $1,500 gain before the excluded items.

These are conditional arithmetic results, with no probabilities attached. Every settlement value at or below 100 produces the same $9,500 ending amount in this model. The bill's $285 gain, less the $780 premium and $5 charge, independently gives the same $500 loss.

A $10,000 face amount changes what the budget can buy

Keep the same fictional bill price of $97 per $100 face value. Bills paying $10,000 at maturity would cost $9,700. Only $300 of the original budget would remain before buying an option or paying costs.

The specified call and opening charge require $785. Buying that call alongside the $10,000 face amount would require $10,485, exceeding the starting budget by $485. Borrowing the difference would add a liability and financing expense; it would not preserve the original unborrowed calculation.

This test does not prescribe a cheaper option. Changing the strike, multiplier, expiration or underlying changes the exposure, and a different whole contract may still fail the budget. OMP's whole-contract loss-budget example examines that sizing problem separately.

Four portfolio limitations

Liquidity

The $9,500 minimum describes the assumed maturity and settlement date. An earlier sale would depend on market prices and transaction costs for both assets. A call can have little resale value, and an executable exit may be unavailable when needed. TreasuryDirect also says that an early Treasury sale requires a bank, broker or dealer; securities held in TreasuryDirect must first be transferred. Account procedures affect access. Money needed on demand may be unsuitable for this arrangement.

Concentration

The call concentrates this example's contingent upside in one index and one expiration. Existing stock and fund holdings can overlap that exposure. Keeping most of the dollars in bills does not make the call diversified, nor does it establish a suitable allocation for a real portfolio.

Time horizon

A later index rise cannot revive an expired call. Nor does a bill's face amount set its resale price before maturity. Matching the two terminal calculations is a narrow assumption, not proof that they fund an earlier spending date. The related bill-maturity and put-expiration article explains why different contract dates need different capital plans.

Funding suitability

The entire $10,000 is committed at inception, including the $5 already spent. There is no separate spending reserve in this example. The purchased cash-settled call creates no modeled share purchase or short-option assignment obligation. Substituting a physically delivered equity call changes that analysis: exercise can require payment for shares, while assignment applies to the corresponding writer. Check the exact contract, broker approval, exercise procedures and settlement timetable. The exercise-versus-assignment guide explains the distinction.

Tax can reduce the spendable ending amount, and treatment of the bill and option can differ by instrument and jurisdiction. A fixed U.S.-dollar amount also does not preserve purchasing power or an Australian-dollar spending target. The conditional floor assumes the Treasury pays as stated, the securities remain held as modeled, and the account can receive and access the proceeds. It is not an insurance policy or a promise against every operational or investment risk.

Record the amount that remains when the call pays zero

Before calling a portfolio capital-preserving, record the starting outlay, bill purchase cost, bill face amount, option premium, all charges and the date proceeds become available. Then calculate the ending amount with a zero option payoff. For this fictional portfolio, that amount is $9,500 against an initial $10,000.

Sources and scope

Researched and updated 22 October 2026, Australia/Brisbane. TreasuryDirect supplies the bill-payment and sale mechanics; OIC supplies the purchased-call loss boundary; Cboe supplies examples of cash-settled, European-style index-option terms. All portfolio amounts, prices, timing alignment and outcomes are fictional author arithmetic. This is not a structured-note analysis, pricing model, return forecast or claim that any specified contract is available.

Read the current OCC options disclosure document and the relevant broker and product specifications before trading. Options involve risk and are not suitable for all investors.

This is Options Matrix Pro's own educational content. OMP is a commercial options-analysis and decision-support platform. This article provides general education, not personal investment, financial, legal or tax advice, and does not assess any reader's objectives, financial situation or needs. See the Options Matrix Pro disclaimer.