Combining Short-Vol Carry With Tail Protection
Selling volatility earns steady premium most of the time but risks catastrophic losses in a crash; pairing it with a small, permanent tail hedge funded partly by that same premium is a common way to keep the carry without betting the fund on the next crash never arriving.
Prerequisites: Short Strangle Programs and Stop Rules, Tail Hedge Monetisation Rules
Selling volatility works, most of the time, because implied volatility tends to trade a bit above the volatility that actually shows up — sellers get paid a small edge for insuring other people against moves that usually don't happen. It also works, most of the time, right up until the day it doesn't: volatility-selling funds have been wiped out or nearly wiped out several times in market history, most famously in February 2018, when a spike in volatility overwhelmed positions sized for calmer markets.
Combining short-vol carry with tail protection means running the premium-selling strategy as before, but permanently spending a slice of that premium on far out-of-the-money options that pay off specifically in the scenario the short-vol book is most exposed to. It converts "sell vol and hope the crash doesn't come on your watch" into "sell vol and own a small parachute either way."
A pure short-volatility book earns steady income most years and can lose everything in one bad one — spending part of that income on a permanent tail hedge trims the average return a little, in exchange for making the strategy survivable through the crash years that eventually come.
Why the combination, not either alone
Pure short-vol carry has an appealing return profile — small, steady gains — until a tail event, when losses can exceed years of accumulated premium in days. Pure tail protection (buying puts with no offsetting income) has the opposite problem: it reliably loses a little money every quiet year and needs a crash just to break even. Combining the two uses the short-vol book's income to fund the tail hedge's persistent cost, producing a strategy whose worst-case loss is far smaller than the short-vol book alone, at a modest cost to its best-case return.
Worked example
A fund's short-vol book earns $5 million a year in a typical calm year and would lose $40 million in a severe crash year, based on historical stress scenarios. The fund spends $1 million a year (20% of typical income) on far out-of-the-money index puts as a permanent tail hedge, which would pay out roughly $25 million in that same severe crash scenario.
- Calm year: net result is , i.e. $4 million, versus $5 million for the unhedged book — a real, but modest, drag.
- Crash year: net result is , i.e. -$15 million, versus a $40 million loss for the unhedged book — the hedge cut the tail loss by nearly two-thirds.
Over many years, the fund gives up roughly 20% of its calm-year income in exchange for a crash year that is a survivable setback rather than an existential one.
What this means in practice
The tail hedge in this combination is usually sized and structured differently from a standalone tail-hedging program — cheaper, further out of the money, and explicitly funded from the short-vol book's own income rather than budgeted separately — because its job is narrowly to offset this specific book's tail risk, not to hedge the whole portfolio. Funds that skip this step are betting, whether they say so or not, that they will be smart or lucky enough to close the short-vol book before the next tail event; funds that run the combination are betting they won't have to be.
Adding a tail hedge reduces the size of a crash loss, but for a short-vol book sized aggressively enough, it does not guarantee solvency — the hedge is calibrated to a stress scenario, and if the actual crash is larger or the correlations behave differently than assumed, the combined strategy can still suffer damage well beyond what the backtest implied.
Related concepts
Practice in interviews
Further reading
- Sinclair, Volatility Trading (ch. on tail-risk hedged carry)