Sandisk vs Seagate Technology Holdings plc (SNDK vs STX) 2026: Stock Returns, Risk & Volatility

Q: Which is a better investment: SNDK or STX?

Over the past year, SNDK looks like the better investment: it had higher total return (SNDK +2738.4% vs STX +618.3%) and a higher Sharpe ratio (SNDK 4.01 vs STX 3.49). On risk, STX was less volatile (STX 61.5% vs SNDK 94.9%), STX had a smaller max drawdown (STX -21.1% vs SNDK -31.3%), and STX had less severe losses on the worst 5% of days (Expected Shortfall of STX -7.25% vs SNDK -11.43%).

Written by Gale Finance Team

Reviewed by Sid Kalla CFA Charterholder

Quick answer

Which is a better investment: SNDK or STX?

Over the past year, SNDK outperformed STX. SNDK returned +2738.4% compared with STX’s +618.3%. SNDK had the better risk-adjusted return, with a Sharpe ratio of 4.01 versus STX’s 3.49. STX was less volatile than SNDK, and STX had a smaller max drawdown than SNDK.

Total Return

SNDK +2738.4%

STX +618.3%

Sharpe Ratio

SNDK 4.01

STX 3.49

Annualized Volatility

SNDK 94.9%

STX 61.5%

Max Drawdown

SNDK -31.3%

STX -21.1%

Metric winners: Total Return: SNDK; Sharpe Ratio: SNDK; Annualized Volatility: STX (less volatile); Max Drawdown: STX (smaller drawdown).

SNDK Total Return

↑ +2738.4%

STX Total Return

↑ +618.3%

Relative Performance of SNDK vs STX (Normalized to 100)

SNDK STX

Normalized to 100 at start date for comparison

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Key Takeaways

Total Return: SNDK delivered a +2738.4% total return, while STX returned +618.3% over the same period. SNDK outperformed on total returns.
Risk-Adjusted Return (Sharpe Ratio): SNDK had a higher Sharpe (4.01 vs 3.49), indicating better risk-adjusted performance.
Volatility (Annualized): SNDK was more volatile, with 94.9% annualized volatility, versus 61.5% for STX.
Maximum Drawdown: STX's maximum drawdown was -21.1%, while SNDK experienced a deeper drawdown of -31.3%.
Tail Risk (VaR & Expected Shortfall): At the 5% level (daily log returns), SNDK's VaR was -7.00% and its Expected Shortfall (CVaR) was -11.43%; STX's were -5.88% and -7.25%. VaR is the cutoff; Expected Shortfall is the average move on the worst days.
Skew & Kurtosis: Skew: SNDK 0.06 vs STX 0.59. Excess kurtosis: SNDK 2.12 vs STX 2.74. Negative skew leans downside; higher excess kurtosis means fatter tails.
Tail Days & Extremes: 2σ tail days (down/up): SNDK 6/9, STX 10/6. Worst day: SNDK -20.33% (2025-11-20) vs STX -8.71% (2026-01-30). Best day: SNDK +27.56% (2026-01-06) vs STX +19.14% (2026-01-28).
Risk ratios: Sortino - SNDK: 7.51 vs. STX: 6.49 , Calmar - SNDK: 89.28 vs. STX: 29.67 , Sterling - SNDK: 150.93 vs. STX: 37.90 , Treynor - SNDK: 1.12 vs. STX: 1.08 , Ulcer Index - SNDK: 10.29% vs. STX: 7.05%

Investment Comparison

If you invested $10,000 in each asset on April 25, 2025:

SNDK $283,844.75 +2738.4%

STX $71,827.38 +618.3%

Difference: $212,017.37 (SNDK ahead)

Sandisk vs Seagate Technology Holdings plc Performance Over Time

Metric	SNDK	STX
30 Days	32.7%	38.5%
90 Days	96.8%	69.8%
180 Days	400.9%	151.6%
1 Year	2738.4%	618.3%

Shorter time frames can show different leaders as market conditions change. Consider your investment horizon when comparing performance.

Sandisk vs Seagate Technology Holdings plc Correlation

Average Correlation

moderately correlated

0.55

Current (30-day) 0.70

30-day rolling range +0.08 to +0.84

Sandisk and Seagate Technology Holdings plc are moderately correlated over the past year. With a correlation of 0.55, these assets show moderate co-movement, offering some diversification when held together.

For portfolio construction, this moderate correlation offers some diversification benefit, though the assets still tend to move together during major market moves.

Metric	Value
Current (30-day)	0.70
Average (full period)	0.55
Minimum (30-day rolling)	0.08
Maximum (30-day rolling)	0.84

Correlation measures how closely two assets move together. Values near +1 indicate strong co-movement, near 0 indicates independence, and negative values indicate inverse movement. Current, minimum, and maximum figures are 30-day rolling correlations on shared daily returns.

Drawdown

Maximum Drawdown

SNDK

-31.3%

STX

-21.1%

Sandisk experienced its maximum drawdown of -31.3% from 2025-11-12 to 2025-12-03. It took 34 days to recover.

Seagate Technology Holdings plc experienced its maximum drawdown of -21.1% from 2026-01-29 to 2026-03-06. It took 31 days to recover.

Smaller drawdowns and faster recoveries indicate lower downside risk and greater resilience during market stress.

Sandisk vs Seagate Technology Holdings plc Volatility (SNDK vs STX)

SNDK Volatility

94.9%

±5.98% 1-day vol

STX Volatility

61.5%

±3.88% 1-day vol

1-day volatility (1σ)

SNDK

±5.98%

STX

±3.88%

Sandisk's 94.9% annualized volatility translates to about ±5.98% one-standard-deviation daily volatility.

Seagate Technology Holdings plc's 61.5% annualized volatility translates to about ±3.88% one-standard-deviation daily volatility.

SNDK had the wider volatility profile over this window. That means its day-to-day return distribution was broader; STX was calmer, but lower volatility does not by itself mean better returns.

Treat the ± daily figure as a one-standard-deviation estimate from historical returns, not a forecast or expected absolute daily move. For context, 15-18% annualized volatility is roughly ±1% one-standard-deviation daily volatility.

Risk-adjusted ratios

Sharpe Ratio of SNDK and STX

Sharpe Ratio: SNDK vs. STX

Return per total volatility

Sharpe gives us excess return per unit of risk. Upside and downside volatility both count as risk.

Higher is better

excess return / total volatility

Formula

\displaystyle \mathrm{Sharpe} = \frac{\mathbb{E}[R] - R_f}{\sigma_R}

Sharpe ratio measures return per unit of risk (volatility). A higher Sharpe indicates better risk-adjusted performance. SNDK had a higher Sharpe (4.01 vs 3.49), indicating better risk-adjusted performance.

A Sharpe above 1.0 is generally considered good, above 2.0 is excellent. Negative Sharpe means the asset underperformed the risk-free rate. Calculated on each asset's full 365-day lookback of available prices and annualized using the asset calendar (365 for crypto, 252 trading days for equities/ETFs/metals).

Sortino Ratio of SNDK and STX

Sortino Ratio: SNDK vs. STX

Return per downside volatility

Sortino keeps the return-over-risk idea, but only returns below the target rate count as volatility.

Higher is better

excess return / downside volatility

Formula

\displaystyle \mathrm{Sortino} = \frac{\mathbb{E}[R] - R_f}{\sigma_{\mathrm{down}}}

Sortino ratio measures return per unit of downside risk. Unlike Sharpe, it only counts downside deviation (returns below the target return). SNDK had better downside-adjusted returns.

A higher Sortino is better. It's useful when upside volatility is common (crypto is the obvious example). Downside deviation: SNDK 50.7% vs STX 33.1%. Calculated on each asset's full 365-day lookback of available prices, using the daily risk-free rate as the target return, and annualized using the asset calendar (365 for crypto, 252 trading days for equities/ETFs/metals).

Calmar Ratio of SNDK and STX

Calmar Ratio: SNDK vs. STX

CAGR per worst drawdown

Calmar compares CAGR against the single deepest peak-to-trough loss over the period.

Higher is better

CAGR / max drawdown

Formula

\displaystyle \mathrm{Calmar} = \frac{\mathrm{CAGR}}{|\mathrm{MaxDD}|}

Calmar ratio compares CAGR to maximum drawdown. Higher Calmar means more return per unit of worst drawdown. SNDK posted the higher Calmar ratio.

Calmar is computed on each asset's full 365-day lookback and uses the max drawdown over that same window.

Sterling Ratio of SNDK and STX

Sterling Ratio: SNDK vs. STX

Return per average drawdown

Sterling smooths the drawdown penalty by using average drawdown events instead of only the worst one.

Higher is better

excess annual return / average deep drawdown

Formula

\displaystyle \mathrm{Sterling} = \frac{\mathrm{CAGR} - R_f}{\overline{D}_{>10\%}}

Sterling ratio measures excess return per unit of average drawdown (typically drawdowns worse than 10%). SNDK posted the higher Sterling ratio.

Sterling uses average drawdown events deeper than 10% and subtracts the risk-free rate to report excess return.

Treynor Ratio of SNDK and STX

Treynor Ratio: SNDK vs. STX

Excess return per market beta

Treynor divides excess annualized return by beta — the sensitivity of the asset to broad-market moves. The slope shown is each asset’s beta vs SPY.

Higher is better

excess return / market beta

Formula

\displaystyle \mathrm{Treynor} = \frac{\mathbb{E}[R] - R_f}{\beta}

Treynor ratio measures excess return per unit of market risk (beta) instead of total volatility. SNDK posted the higher Treynor ratio.

Treynor uses beta vs the S&P 500 (SPY) on shared dates and the average 3-month Treasury rate as the risk-free rate.

Ulcer Index of SNDK and STX

Ulcer Index: SNDK vs. STX

Drawdown pain

Ulcer Index is a risk index, not a return-over-risk ratio. Lower means smaller and shorter drawdowns.

Lower is better

root-mean-square drawdown

Formula

\displaystyle \mathrm{UI} = \sqrt{\mathbb{E}[D_t^2]}

Ulcer Index captures drawdown depth and duration. Lower Ulcer Index means less drawdown pain. STX had the lower Ulcer Index (less drawdown pain).

Ulcer Index is computed from each asset's drawdown series over the full lookback window.

Tail Risk & Distribution Shape (1-Year): Sandisk vs. Seagate Technology Holdings plc

This section looks at the shape of daily returns, not just the average. Tail stats are computed per asset on its own daily series (crypto includes weekends). We use daily log returns $\ln\left(\frac{P_t}{P_{t-1}}\right)$ so multi-day moves add cleanly.

Definitions: Value at Risk (VaR), Expected Shortfall, skew, kurtosis, and fat tails.

Tail Risk & Distribution Shape: SNDK vs. STX (1-Year)

Actual daily return tails

The bars are real daily log-return observations from the article window. Darker bars are observations at or beyond each asset’s 5% VaR cutoff.

Observed returns

VaR marks the 5th percentile loss cutoff; Expected Shortfall averages the observations beyond that cutoff.

Formula

\displaystyle \mathrm{VaR}_{5\%}=Q_{0.05}(r_t),\quad \mathrm{ES}_{5\%}=\mathbb{E}[r_t\mid r_t\le \mathrm{VaR}_{5\%}]

Metric (1-Year)	SNDK	STX
5% VaR (daily log return)	-7.00%	-5.88%
5% Expected Shortfall (CVaR)	-11.43% (worst 13 days)	-7.25% (worst 13 days)
Skew	0.06	0.59
Excess kurtosis	2.12	2.74
2σ tail days (down / up)	6 / 9	10 / 6
Worst day	-20.33% (2025-11-20)	-8.71% (2026-01-30)
Best day	+27.56% (2026-01-06)	+19.14% (2026-01-28)

Downside co-moves (2σ) — 1-Year

Computed on shared dates only (n=249). A “2σ downside move” means a shared-close log return more than 2 standard deviations below that asset’s own mean on this shared-date series. Dates below show simple returns (%) for readability.

Downside co-move map: SNDK vs. STX (2σ)

Shared-close daily returns

Dots mark actual downside days: asset-colored dots are one-sided downside moves, and red dots are joint downside days. Grey dots add sampled shared-return context when available. The shaded lower-left zone shows where both SNDK and STX crossed their own 2σ downside threshold.

2σ

Show downside tail dates

Dates below are shared-date observations. The “Date” is the period end (close). Tail thresholds are computed on log returns, but the table shows simple returns (%) for readability. Returns are computed from the previous shared close to this one (for example, Friday → Monday includes weekend moves).

Days when both SNDK and STX had a big down day (2σ)

Date (interval)	SNDK	STX
2025-11-13	-13.96%	-7.31%
2025-11-20	-20.33%	-7.19%
2025-12-12	-14.66%	-6.56%
2026-03-26	-11.02%	-8.33%

Days when SNDK had a big down day

Date (interval)	SNDK	STX
2025-10-10	-9.85%	-3.30%
2025-11-13	-13.96%	-7.31%
2025-11-20	-20.33%	-7.19%
2025-12-12	-14.66%	-6.56%
2026-02-04	-15.95%	-5.81%
2026-03-26	-11.02%	-8.33%

Days when STX had a big down day

Date (interval)	SNDK	STX
2025-10-07	-0.18%	-7.34%
2025-11-13	-13.96%	-7.31%
2025-11-20	-20.33%	-7.19%
2025-12-12	-14.66%	-6.56%
2026-01-07	+1.12%	-6.71%
2026-01-08	-5.38%	-7.72%
2026-01-30	+6.85%	-8.71%
2026-02-10	-7.16%	-6.77%
2026-02-27 → 2026-03-02	-2.56%	-6.94%
2026-03-26	-11.02%	-8.33%

Read this as “how ugly the ugly days get”, not as a precise forecast. One-year samples are small, so tail estimates are inherently noisy.

Full Comparison of Sandisk vs. Seagate Technology Holdings plc (1-Year)

Metric	SNDK	STX
Total Return	+2738.4%	+618.3%
Annualized Volatility	94.9%	61.5%
Sharpe Ratio	4.01	3.49
Sortino Ratio	7.51	6.49
Calmar Ratio	89.28	29.67
Sterling Ratio	150.93	37.90
Treynor Ratio	1.12	1.08
Ulcer Index	10.29%	7.05%
Max Drawdown	-31.3%	-21.1%
Avg Correlation to S&P 500	0.48	0.38
5% VaR (daily log return)	-7.00%	-5.88%
5% Expected Shortfall (CVaR)	-11.43%	-7.25%
Skew	0.06	0.59
Excess kurtosis	2.12	2.74
2σ tail days (down / up)	6 / 9	10 / 6

Audit this calculation

Formulas, inputs, and conventions used to compute the metrics on this page.

Inputs & conventions

Shared window for pair metrics: 2025-04-25 → 2026-04-23 (last shared close).
Rolling correlation sample (shared closes): 220 rolling 30-day values (from 249 shared daily returns).
Annualization (days/year): SNDK: 252 days/year; STX: 252 days/year.
Risk-free rate: Uses the 3-month U.S. Treasury yield (FRED: DGS3MO), averaged over each asset’s window:

SNDK: 4.17% over 2025-04-25 → 2026-04-23.

STX: 4.17% over 2025-04-25 → 2026-04-23.
Volatility drag (rule of thumb): Estimated from annualized volatility (simple returns). For the log-return framing, see Log returns.

SNDK: ≈ -45.0%/yr

STX: ≈ -18.9%/yr
Data alignment: No forward fill. Correlation and tail co-moves are computed on shared closes only.
For cross-calendar pairs (e.g., crypto vs stocks), weekend/holiday moves roll into the next shared close.
Return conventions: Volatility/Sharpe/Sortino use simple daily returns. Tail-risk uses daily log returns for distribution stats (but tables show simple returns). Log returns.

Formulas

Daily simple return

r_t = \frac{P_t}{P_{t-1}} - 1

Volatility

\sigma_{ann} = \sigma(r_t)\sqrt{A}

Volatility drag (approx.)

\text{drag} \approx \tfrac{1}{2}\sigma_{ann}^2

Sharpe Ratio

S = \frac{A\,\bar{r} - r_f}{\sigma(r_t)\sqrt{A}}

Sortino Ratio

So = \frac{A\,\bar{r} - r_f}{\sqrt{\mathbb{E}[\min(0,\,r_t - r_f/A)^2]}\,\sqrt{A}}

Maximum Drawdown

MDD = \min_t\left(\frac{P_t}{\max_{s \le t} P_s} - 1\right)

Average Correlation

\rho = \frac{\operatorname{cov}(r^A,\,r^B)}{\sigma_A\,\sigma_B}

Log returns

\ell_t = \ln\left(\frac{P_t}{P_{t-1}}\right)

Notation

$P_t$: Price on day t.
$r_t$: Simple daily return.
$\ell_t$: Log daily return.
$\bar{r}$: Average daily return.
$\sigma(r_t)$: Standard deviation of daily returns.
$A$: Annualization factor (days/year).
$r_f$: Annual risk-free rate.

Sandisk vs Seagate Technology Holdings plc: Frequently Asked Questions

Which has higher volatility: SNDK or STX?

SNDK showed higher volatility at 94.9% annualized, compared to 61.5% for STX Over the past year. Higher volatility means larger price swings in both directions.

Does SNDK provide diversification when held with STX?

SNDK and STX are moderately correlated over the past year, with an average correlation of 0.55. This offers some diversification benefit, though they still tend to move together during major market moves.

How bad are the worst 5% days for SNDK vs STX?

Over the past year, SNDK's 5% VaR was -7.00% and its 5% Expected Shortfall was -11.43% (worst 13 days). STX's were -5.88% and -7.25% (worst 13 days).

Do SNDK and STX crash together on bad days?

On shared dates (n=249), when STX has a 2σ down day, SNDK also does 40.0% (4/10 days). In the other direction, when SNDK has one, STX also does 66.7% (4/6 days).

Which has better risk-adjusted returns: SNDK or STX?

SNDK showed better risk-adjusted performance with a Sharpe ratio of 4.01 versus STX's 3.49 Over the past year.

Can SNDK and STX be combined in a portfolio?

Yes, though allocation sizing matters. Their moderate correlation offers some diversification benefits. SNDK's higher volatility (94.9%) means even small allocations can materially impact overall portfolio risk.

Explore our financial glossary

Which is a better investment: SNDK or STX?

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Relative Performance of SNDK vs STX (Normalized to 100)

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Key Takeaways

Investment Comparison

Sandisk vs Seagate Technology Holdings plc Performance Over Time

Sandisk vs Seagate Technology Holdings plc Correlation

Drawdown

Sandisk vs Seagate Technology Holdings plc Volatility (SNDK vs STX)

Risk-adjusted ratios

Sharpe Ratio of SNDK and STX

Sharpe Ratio: SNDK vs. STX

Sortino Ratio of SNDK and STX

Sortino Ratio: SNDK vs. STX

Calmar Ratio of SNDK and STX

Calmar Ratio: SNDK vs. STX

Sterling Ratio of SNDK and STX

Sterling Ratio: SNDK vs. STX

Treynor Ratio of SNDK and STX

Treynor Ratio: SNDK vs. STX

Ulcer Index of SNDK and STX

Ulcer Index: SNDK vs. STX

Tail Risk & Distribution Shape (1-Year): Sandisk vs. Seagate Technology Holdings plc

Tail Risk & Distribution Shape: SNDK vs. STX (1-Year)

Downside co-moves (2σ) — 1-Year

Downside co-move map: SNDK vs. STX (2σ)

Days when both SNDK and STX had a big down day (2σ)

Days when SNDK had a big down day

Days when STX had a big down day

Full Comparison of Sandisk vs. Seagate Technology Holdings plc (1-Year)

Inputs & conventions

Formulas

Sandisk vs Seagate Technology Holdings plc: Frequently Asked Questions

Which has higher volatility: SNDK or STX?

Does SNDK provide diversification when held with STX?

How bad are the worst 5% days for SNDK vs STX?

Do SNDK and STX crash together on bad days?

Which has better risk-adjusted returns: SNDK or STX?

Can SNDK and STX be combined in a portfolio?