Greenman William Mariner
Director · Officer · CERS
As of 2026-09-16, Greenman William Mariner has 18 Form 4 transactions on record across 1 company — 6 in the trailing 12 months.
Everything this person has disclosed to the SEC on Form 4 — across every company they file for — reconstructed from the public record. A filing history, not a tip sheet.
Pattern in the record: open-market sales filed in March in multiple years since 2025 — a recurring calendar cadence, more consistent with scheduled activity than a one-off decision.
Reconstructed holdings
- Direct $12.8M
- Indirect $0
| CERS | direct | 5,053,036 sh | $12.8M |
Reconstructed from this person's own Form 4 filings — the total each filing reported owning afterward, priced at the close on the as-of date shown. A filed position can lag the real one.
Direct and indirect holdings (e.g. through a trust or fund) are tagged separately, as filed.
Trades by company
Filing ledger
| Date | Company | Action | Shares @ price | Value | Ownership Δ | Owned after | Filing |
|---|---|---|---|---|---|---|---|
| 2026-06-30 | CERS | Sale | 101,919 @ $2.94 | $300K | −2.0% of holding | 5,053,036 | Form 4 |
| 2026-03-12 | CERS | Sale | 447,757 @ $1.66 | $742K | −8.2% of holding | 4,998,493 | Form 4 |
| 2026-03-06 | CERS | Sale | 78,187 @ $2.01 | $157K | −1.4% of holding | 5,446,250 | Form 4 |
| 2025-03-14 | CERS | Sale | 122,827 @ $1.45 | $178K | −2.9% of holding | 4,115,845 | Form 4 |
| 2025-03-13 | CERS | Sale | 71,086 @ $1.45 | $103K | −1.6% of holding | 4,238,672 | Form 4 |
| 2025-03-07 | CERS | Sale | 60,984 @ $1.50 | $91K | −1.4% of holding | 4,309,758 | Form 4 |
| 2025-03-04 | CERS | Sale | 23,023 @ $1.55 | $36K | −0.7% of holding | 3,230,000 | Form 4 |
11 award / exercise / gift records — not counted as purchases
| Date | Company | Action | Shares | Owned after | Filing |
|---|---|---|---|---|---|
| 2026-06-30 | CERS | Award / grant | 192,500 | 5,154,955 | Form 4 |
| 2026-03-05 | CERS | Award / grant | 193,270 | 5,524,437 | Form 4 |
| 2026-03-02 | CERS | Award / grant | 1,200,000 | 5,331,167 | Form 4 |
| 2025-03-06 | CERS | Award / grant | 975,000 | 4,205,000 | Form 4 |
| 2025-03-06 | CERS | Award / grant | 165,742 | 4,370,742 | Form 4 |
| 2025-03-03 | CERS | Option exercise | 57,637 | 3,253,023 | Form 4 |
| 2025-03-03 | CERS | Option exercise | 57,637 | 0 | Form 4 |
| 2025-03-03 | CERS | Option exercise | 57,637 | 3,253,023 | Form 4 |
| 2025-03-03 | CERS | Option exercise | 57,637 | 0 | Form 4 |
| 2025-02-26 | CERS | Award / grant | 57,637 | 57,637 | Form 4 |
| 2025-02-26 | CERS | Award / grant | 57,637 | 57,637 | Form 4 |
Source: SEC Form 4 filings. Each row links to its original filing.
Research tool, not investment advice — historical frequencies, not recommendations. A product of Marovel Technologies LLC. Full terms.