Spinoff Tracker

Every US corporate spin-off, sourced from the filing that proves it.

WESTERN DIGITAL CORP WDC → Sandisk Corporation SNDK

Distribution2025-02-21
Return+3184.12%
ParentWESTERN DIGITAL CORP WDC
SpincoSandisk Corporation SNDK
StatusCompleted
StructureSpin-off A filing states a pro-rata distribution: holders receive shares automatically.
FocusNot focus-increasing Parent and spinco remain in the same industry; the separation divides scale rather than business.
Ratio1 Sandisk share for every 3 Western Digital shares
Parent retains19.9%
When-issued tickerSNDKV
Checked against EDGAR2026-08-22

Data trap

Two share counts and a typo. The first quarterly report gave 114,863,251 shares on its cover; an amendment filed ten days later corrected that to 144,863,251, which is the figure that matches the information statement. Anything that scraped the original cover carries a count 30 million shares light. Separately, roughly 115 million shares were actually distributed against 144.9 million outstanding, because Western Digital retained 19.9 percent to unwind later through debt-for-equity exchanges.

The restated filings have landed; this is kept as history.

Catalyst clock

  1. 2023-10-30Separation announced
  2. 2024-11-25Form 10 filed
  3. 2025-01-27Form 10 last amended
  4. 2025-01-31Form 10 effective
  5. 2025-02-12Record date
  6. 2025-02-13When-issued trading opens
  7. 2025-02-21Distribution
  8. 2025-05-07First standalone earnings
  9. —Index inclusion announced

Performance since separation

Sandisk Corporation since separation+3184.12%
WESTERN DIGITAL CORP over the same window+784.90%
S&P 500 (SPY) over the same window+27.63%
Russell 2000 (IWM) over the same window+37.72%
Excess over the S&P 500+3156.49%
Excess over the Russell 2000+3146.40%

Measured from the first regular-way close on or after the distribution — 2025-02-24 at 48.60 — to 2026-08-21 at 1596.08. Window: 1.5 years. The 2025-02-21 session was skipped: it traded on when-issued volume, not regular-way, and pricing from it would measure the return against a market that no longer existed the next day. Two benchmarks, because one is misleading: spin-offs are usually small companies, and across this period small caps lagged the S&P by several points a year on their own. Measured against the S&P alone, roughly a third of any shortfall is company size rather than the separation. Returns are arithmetic over end-of-day closing prices. Unlike every other figure on this page, they do not come from a filing.

Pre-distribution investor return

Parent, announcement to separation+70.53%
Combined (WESTERN DIGITAL CORP + Sandisk Corporation), pre-distribution to now+1740.48%
Combined excess over the S&P 500+1715.03%
Combined excess over the Russell 2000+1706.72%

Combined treats a pre-spin holding as 1 Sandisk share for every 3 Western Digital shares valued at the parent's last close before regular post-spin trading resumed — 2025-02-20 at 53.87 — against that same basket today. That baseline is a practical proxy, not an attempt to isolate exactly how much value the separation transferred: for a large parent and a small spinco, ordinary day-to-day price noise can be bigger than the transfer itself. Run-up measures only the parent's own price, from the announcement date to that same baseline — how far the market had already moved before the separation's mechanics ever happened.

Filings

Every fact on this page comes from one of these.

Notes

Western Digital's separation of its NAND flash business, restoring Sandisk as an independent company. The distribution took effect at 11:59 p.m. Pacific on February 21, so regular-way trading began the following session. Classified non-focus-increasing: both companies remain storage-device makers under the same four-digit SIC, and the split is between flash and hard-disk technologies rather than between industries.