Call Warrant Position Sizing and Volatility Crush
A trader is evaluating a JSE-listed cash-settled call warrant on a share trading at R120.00. The warrant has a strike of R110.00, a ratio of one warrant per share, 120 days to expiry, and is offered at R14.50. The share's implied volatility is 30% and the warrant's implied volatility is 34%. The risk-free rate is 8.00% and the share pays no dividend. The trader has R145,000 to invest and is considering either 10,000 warrants or 1,208 shares, ignoring costs. The warrant's delta is 0.58, theta is -R0.035 per warrant per day, and vega is R0.08 per warrant for each 1 percentage point change in implied volatility. The trader expects the share to rise to R132.00 in 30 days but is concerned about time decay and a volatility crush after an upcoming earnings announcement. The issuer's bid-offer spread is 2%.
1. Calculate intrinsic value, time value, gearing, delta-adjusted exposure and effective gearing for the warrant. Compare the notional exposure of 10,000 warrants with 1,208 shares.
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- Intrinsic value = max(120 − 110, 0) = R10.00.
- Time value = 14.50 − 10.00 = R4.50.
- Gearing = share price / warrant price = 120 / 14.50 = 8.28x.
- Delta-adjusted exposure per warrant = 0.58 × R120 = R69.60.
- Effective gearing = 69.60 / 14.50 = 4.80x.
For 10,000 warrants:
- Cost = 10,000 × 14.50 = R145,000.
- Delta-adjusted exposure = 10,000 × 69.60 = R696,000.
For 1,208 shares:
- Cost ≈ 1,208 × 120 = R144,960.
- Exposure = R144,960.
The warrant position gives about 4.8 times the share exposure for the same capital. That is the point of the warrant, but it also means losses accelerate if the share falls or implied volatility drops.
2. Estimate the warrant price after 30 days if the share reaches R132.00, delta is 0.58, theta is -R0.035 per day, implied volatility falls from 34% to 28%, and vega is R0.08 per volatility point.
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Use a first-order approximation:
- Delta gain = 0.58 × (132 − 120) = 0.58 × 12 = R6.96.
- Theta decay = −0.035 × 30 = −R1.05.
- Volatility change = 28% − 34% = −6 points; vega effect = −6 × 0.08 = −R0.48.
Estimated warrant price ≈ 14.50 + 6.96 − 1.05 − 0.48 = R19.93.
Return on the warrant = (19.93 − 14.50) / 14.50 ≈ 37.4%. The share return is (132 − 120) / 120 = 10.0%. The warrant therefore delivers roughly 3.7x the share return after decay and volatility crush. If implied volatility had stayed at 34%, the estimate would be R20.41, or 40.8%; the volatility crush costs about 3.4 percentage points of return.
3. Assess the main risks of the warrant versus buying shares, including expiry, issuer credit, liquidity and volatility. Would you recommend the warrant for a 30-day directional view?
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The warrant is not a simple leveraged share position. Key risks:
- Time decay: theta costs about R1.05 over 30 days, roughly 7% of the current warrant price.
- Volatility risk: the warrant trades at 34% implied volatility versus 30% for the share. A post-earnings crush can wipe out a large part of the delta gain.
- Expiry: at expiry the warrant is worth only intrinsic value. Breakeven at expiry is strike plus price = 110 + 14.50 = R124.50, so the share must rise about 3.75% just to avoid a loss, before dealing costs.
- Issuer credit: the warrant is an obligation of the issuing bank, not the exchange; the investor is exposed to issuer default.
- Liquidity and spread: a 2% bid-offer spread is a real cost, especially for a short holding period.
For a 30-day directional view, the warrant can be justified only if the expected move is large enough to overcome theta, vega and spread. A move to R132 is plausible, but the position should be modest because the volatility crush risk is concentrated around the earnings date. A share position or a smaller warrant position with a defined exit is more prudent for a low-conviction view.