ZSTK — ZeroStack Corp.
Price · 2024-08-26 → 2026-08-21
499 daily closes shownAnonymous view is capped at two years of history. A free account extends it to five, and Pro opens the whole archive back to 2021-05-11.
Performance
Technicals
Others in Healthcare
Measured signals that fired on ZSTK
| date | signal | measured base rate |
|---|---|---|
| 2026-07-20 | Conviction buy by an officer insider | -1.03% over 21 days · t = -2.24 · n = 1,083 statistically distinguishable from its control group |
Excess return against a matched control group, on a point-in-time universe that includes delisted companies. Most families do not survive that. How the measurement works →
Insider transactions (Form 4)
| date | insider | what | shares | price | value |
|---|---|---|---|---|---|
| 2026-08-19 | Rong Rudy President | Open-market sale | 1.0K | 7.57 | 7.6K |
| 2026-07-20 | Heinrich Michael Executive Chairman | Open-market purchase | 4.6M | 0.75 | 3.5M |
| 2026-07-20 | Reis-Faria Daniel CEO | Option Exercise | 6.0M | 0.00 | 595 |
| 2024-12-15 | WOO EDWARD Director | Grant or award | 50.0K | — | — |
| 2024-12-15 | Starke Clifford CEO | Grant or award | 900.0K | — | — |
| 2024-12-15 | DORF SAMMY Executive Chairman | Grant or award | 250.0K | — | — |
| 2024-09-13 | Starke Clifford CEO | Open-market purchase | 6.8K | 0.95 | 6.5K |
| 2024-09-06 | Wolkin Harold Director | Open-market purchase | 15.0K | 0.98 | 14.7K |
| 2024-09-06 | Wolkin Harold Director | Open-market purchase | 5.0K | 0.96 | 4.8K |
| 2024-09-06 | Wolkin Harold Director | Open-market purchase | 5.0K | 0.95 | 4.8K |
Open-market purchases (code P) are the informative ones. Grants, option exercises and tax withholding are compensation mechanics, not decisions. How to read a Form 4 →
Largest institutional holders
| manager | value | shares |
|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC | 157.2K | 25.4K |
| GEODE CAPITAL MANAGEMENT, LLC | 156.5K | 25.3K |
| VANGUARD FIDUCIARY TRUST CO | 78.2K | 12.6K |
| UBS Group AG | 4.1K | 666 |
| MORGAN STANLEY | 1.1K | 173 |
| Bernard Wealth Management Corp. | 75 | 12 |
| OSAIC HOLDINGS, INC. | 73 | 12 |
| Sound Income Strategies, LLC | 72 | 12 |
| Key Financial Inc | 6 | 1 |
| ROYAL BANK OF CANADA | 0 | 12 |
13F positions as of 2026-03-31, filed up to 45 days after quarter end. Long-only US equity — shorts and derivatives never appear. What 13F does and does not show →
Latest SEC filings
| form | filed | period | |
|---|---|---|---|
| 8-K | 2026-08-19 | 2026-08-19 | on EDGAR ↗ |
| S-4 POS | 2026-08-18 | — | on EDGAR ↗ |
| 8-K12B | 2026-08-18 | 2026-08-18 | on EDGAR ↗ |
| 10-Q | 2026-07-31 | 2026-06-30 | on EDGAR ↗ |
| D | 2026-07-29 | — | on EDGAR ↗ |
| 8-K | 2026-07-23 | 2026-07-20 | on EDGAR ↗ |
| SCHEDULE 13D/A | 2026-07-21 | — | on EDGAR ↗ |
| SCHEDULE 13D/A | 2026-07-21 | — | on EDGAR ↗ |
Short selling
This is off-exchange short volume, not short interest: it is flow, not position, and 40–50% is normal because market makers short to fill your buy. Why that number misleads →
Recent headlines
- Zerostack Corp. (ZSTK) filed form 8-K · 2026-08-21 · SEC EDGAR
- Zerostack Corp. (ZSTK) filed form 8-K · 2026-08-19 · SEC EDGAR
- ZeroStack Corp. (ZSTK) filed form 8-K · 2026-08-19 · SEC EDGAR
- Zerostack Corp. (ZSTK) filed form 8-K12B · 2026-08-18 · SEC EDGAR
- ZeroStack Corp. (ZSTK) filed form S-4 POS · 2026-08-18 · SEC EDGAR
- ZeroStack Corp. (ZSTK) filed form 8-K12B · 2026-08-18 · SEC EDGAR
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