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SPXS Basics and the 'Insurance' Concept

SPXS (Direxion Daily S&P 500 Bear 3X Shares) is an inverse ETF targeting -3x the daily return of the S&P 500 index. With a 1.01% expense ratio, managed by Direxion. Since it profits when the S&P 500 declines, the idea naturally arises: could it serve as portfolio 'insurance'?

The insurance concept works like this: allocate 5% of your portfolio to SPXS. During normal times, SPXS continuously decays, which you treat as an 'insurance premium.' When a crash arrives, SPXS surges, delivering an 'insurance payout' that mitigates overall portfolio losses.

This idea is intuitively appealing, but mathematical analysis reveals that in most cases, the 'premium is too expensive.' Let's calculate the specifics.

Calculating Decay Cost - Monthly, Quarterly, Annual

Assuming S&P 500 daily volatility of 1.0% (annualized ~16%), SPXS's monthly decay approximates -9 x (0.01)^2 x 21 / 2 = -0.95% (21 trading days per month). Adding the trend factor (S&P 500 average monthly return +0.8%) at -3x = -2.4%, the monthly expected loss is approximately -3.4%.

Compounding produces roughly -10% quarterly and -35% annually. With 5% of your portfolio in SPXS, the annual 'insurance premium' equals 1.75% of total portfolio value (5% x 35%).

Given the S&P 500's long-term average annual return of +10%, a 1.75% premium consumes 17.5% of returns every year. Over 10 years, the cumulative cost through compounding becomes non-trivial.

Break-Even Calculation - How Large a Crash Is Needed?

SPXS's one-month decay cost is approximately -3.4%. To recoup this 'premium,' how much must the S&P 500 fall within one month? Since SPXS is -3x, a -1.13% S&P 500 decline produces +3.4% in SPXS, offsetting the decay. But this merely breaks even.

For insurance to actually function, the S&P 500 must fall much further. Assuming 95% of your portfolio tracks the S&P 500, a -20% crash produces -19% portfolio loss (95% x -20%). Meanwhile, the 5% SPXS allocation gains +60% (= -3 x -20%), generating +3%. Net loss: -16%.

Compared to -20% without SPXS, that is a 4% loss reduction. However, if this -20% crash does not occur within a year, the -1.75% annual premium is wasted. Two years without a crash means -3.5% in costs. Statistically, the probability of the S&P 500 falling -20%+ in any given year is approximately 5%, making the expected value of insurance payouts lower than premiums paid.

Comparison with Put Options

As portfolio insurance, put options are often more efficient than SPXS. A 3-month out-of-the-money (5% OTM) S&P 500 put option costs approximately 1-2% of portfolio value.

Put options have the advantage of capping losses at the premium paid. SPXS decays indefinitely as long as the market rises, but a put option simply expires worthless at maturity with no further loss. Additionally, put option payoffs are non-linear, delivering larger insurance payouts for larger crashes.

SPXS's advantage over puts is accessibility and liquidity. Options trading requires a specialized account and knowledge of strike selection and expiration. SPXS trades in any standard brokerage account and can be exited anytime. This convenience is SPXS's raison d'etre, though it is less cost-efficient than options.

Verification with Actual Crash Events

Testing with the March 2020 COVID crash: the S&P 500 fell -34% from February 19 to March 23. SPXS returned over +90% during this period. With 5% allocated to SPXS, that is +4.5% gain, partially offsetting the 95% S&P 500 position's -32.3% loss, for a net -27.8%.

However, if you had held SPXS from January 1, 2020, it would have already decayed approximately -15% during the January-mid-February rally, reducing effective crash returns. Furthermore, failing to exit SPXS after the crash means April's sharp rebound erases all gains.

In the 2022 bear market, the S&P 500 fell -19% for the year. SPXS's annual return was approximately +30% (far below the theoretical +57%). At 5% allocation, that is +1.5% gain against 95% position's -18% loss, netting -16.5%. The insurance effect was just 2.5%, roughly offset by the prior year's premium cost.

Improved Insurance Strategies

Rather than holding SPXS continuously as 'fixed insurance,' a 'timing insurance' approach of buying only when VIX is low (markets are complacent) is more efficient. Buy SPXS when VIX is below 15, sell when VIX exceeds 30.

The advantage: when VIX is low, S&P 500 volatility is also low, meaning SPXS's decay rate is smaller. You buy insurance when premiums are cheap and sell when insurance is needed (VIX spike = crash).

However, this strategy has limits. If low VIX persists for extended periods (as in 2017), decay costs accumulate. Also, crashes often begin suddenly from low-VIX states, meaning 'buy when VIX is low' effectively approaches 'always holding.' Practical risk hedging guides are recommended for understanding the full landscape of hedging strategies.

Conclusion - Too Expensive as Insurance in Most Cases

Using SPXS as portfolio insurance has negative expected value when analyzed mathematically. Annual premium (decay cost) of 1.75% versus statistically lower expected insurance payouts (crash profits).

Insurance 'pays off' only when the S&P 500 crashes -20%+ in a short period, an event with roughly 5% annual probability. Paying 1.75% every year for 20 years to prepare for a once-in-20-year crash is not rational from a compound interest perspective.

For crash protection, raising cash allocation, purchasing put options, or simply reducing position sizes are all more cost-efficient. SPXS should be treated as a 'short-term trading tool,' not 'insurance.'