ZBIO insider buying and SEC filings, explained
Zenas BioPharma, Inc. · CIK 1953926
Tracked: Forms 3/4/5, 8-K, NT · All filings on sec.gov
Insider activity in the last 12 months
Bought
$9.9M
Insiders who bought
4
Sold (not marked 10b5-1)
$0
Planned sales (10b5-1)
$0
Insider purchases and sales, last 12 months
| Traded | Type | What was filed | Source |
|---|---|---|---|
| May 18, 2026 | Purchase (code P) | Leon O. Moulder Jr. (CEO and Director) bought 60,000 shares indirectly at about $16.88 ($1.0M), reported as a purchase (code P). Indirect holdings up 162% to 96,928 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 18, 2026 |
| Apr 28–29, 2026 | Purchase (code P) | Leon O. Moulder Jr. (CEO and Director) bought 60,000 shares indirectly between Apr 28 and Apr 29 at about $17.79 ($1.1M), reported as a purchase (code P). Indirect holdings up 3% to 1,786,039 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Apr 29, 2026 |
| Mar 31, 2026 | Purchase (code P) | Hongbo Lu (Director) bought 3,768 shares indirectly at $18.63 ($70K), reported as a purchase (code P). Indirect holdings up 1% to 426,736 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Apr 2, 2026 |
| Mar 31, 2026 | Purchase (code P) | Peter Evan Harwin (Director) bought 150,000 shares indirectly (by entity) at $20.00 ($3.0M), reported as a purchase (code P). Holdings by entity up 7% to 2,359,025 shares. Not marked as a 10b5-1 plan trade. Filed jointly with 3 other reporting owners. | SEC filing Filed Apr 1, 2026 |
| Mar 31, 2026 | Other purchase | Hongbo Lu (Director) bought 75,000 Common Stock indirectly at $20.00 ($1.5M) in a public offering. Indirect holdings up 22% to 422,968 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 31, 2026 |
| Mar 30–31, 2026 | Purchase (code P) | Leon O. Moulder Jr. (CEO and Director) bought 54,000 shares indirectly between Mar 30 and Mar 31 at about $18.91 ($1.0M), reported as a purchase (code P). Indirect holdings up 3% to 1,726,039 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 31, 2026 |
| Feb 12–13, 2026 | Purchase (code P) | Patricia L Allen (Director) bought 19,860 shares between Feb 12 and Feb 13 at about $25.16 ($500K), reported as a purchase (code P). New position of 19,860 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 13, 2026 |
| Feb 11, 2026 | Purchase (code P) | Hongbo Lu (Director) bought 25,985 shares indirectly at $22.50 ($585K), reported as a purchase (code P). Indirect holdings up 8% to 347,968 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 13, 2026 |
| Feb 2, 2026 | Purchase (code P) | Leon O. Moulder Jr. (CEO and Director) bought 57,000 shares at about $17.96 ($1.0M), reported as a purchase (code P). Holdings up 16% to 423,155 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 3, 2026 |
| Jan 7–9, 2026 | Purchase (code P) | Leon O. Moulder Jr. (CEO and Director) bought 100,000 shares between Jan 7 and Jan 9 at about $16.39 ($1.6M), reported as a purchase (code P). Holdings up 38% to 366,155 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jan 9, 2026 |
11 routine transactions (such as grants, option exercises or tax withholding) are not listed.
Cluster buys
3 insiders bought in 30 days
$6.2M in purchases since Mar 31, 2026 · Purchases traded Mar 31, 2026 to May 18, 2026 · Closed
| Insider | Value | Traded | Source |
|---|---|---|---|
| Leon O. Moulder Jr. (CEO) | $1.0M | Mar 31, 2026 | SEC filing |
| Peter Evan Harwin (Director) | $3.0M | Mar 31, 2026 | SEC filing |
| Hongbo Lu (Director) | $70K | Mar 31, 2026 | SEC filing |
| Leon O. Moulder Jr. (CEO) | $1.1M | Apr 29, 2026 | SEC filing |
| Leon O. Moulder Jr. (CEO) | $1.0M | May 18, 2026 | SEC filing |
3 insiders bought in 30 days
$3.7M in purchases since Jan 9, 2026 · Purchases traded Jan 9, 2026 to Feb 13, 2026 · Closed
| Insider | Value | Traded | Source |
|---|---|---|---|
| Leon O. Moulder Jr. (CEO) | $1.6M | Jan 9, 2026 | SEC filing |
| Leon O. Moulder Jr. (CEO) | $1.0M | Feb 2, 2026 | SEC filing |
| Hongbo Lu (Director) | $585K | Feb 11, 2026 | SEC filing |
| Patricia L Allen (Director) | $500K | Feb 13, 2026 | SEC filing |
Red flags
No red flags in the last 12 months.
Key events
No key events in the last 12 months.
8-K filings, last 12 months
No 8-K filings in the last 12 months.
Red flags are objective triggers only: the item or form filed, never an opinion.
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