Are insiders buying ZBIO stock?

Yes — 11 distinct insiders have bought ZBIO (Zenas BioPharma, Inc.) on the open market, including 4 cluster buys where two or more insiders bought within a rolling window. The most recent qualifying activity was May 18, 2026.

How much ZBIO stock have insiders bought?

Insiders have bought a combined $112.9M of ZBIO across 41 open-market purchases, based on SEC Form 4 filings.

What is an insider cluster buy in ZBIO?

A cluster buy is two or more distinct Zenas BioPharma, Inc. insiders — officers, directors, or 10% owners — each buying ZBIO on the open market within a rolling window. ZBIO has 4 detected cluster buys to date.

Where does this ZBIO insider trading data come from?

Every figure is parsed directly from SEC Form 4 filings on EDGAR, and each purchase on this page links back to its original filing document.

ZBIO insider buying

4 cluster buys

Zenas BioPharma, Inc. · Healthcare

When two or more insiders at Zenas BioPharma, Inc. buy ZBIO on the open market around the same time, that clustered conviction is one of the highest-signal patterns in SEC filing data. Below is every cluster we've detected in ZBIO plus the full record of qualifying open-market buys, each parsed directly from Form 4 filings and linked back to the source on SEC EDGAR.

Clusters

Distinct insiders

Total bought

$112.9M

Market cap

$1.8B

Detected clusters

Mar 30 – Mar 31, 2026
Detected Mar 31, 2026
High conviction2 insiders
Total bought
$2.5M
Market cap
$1.8B
Feb 2 – Feb 13, 2026
Detected Feb 13, 2026
High conviction3 insiders
Total bought
$2.1M
Market cap
$1.8B
Oct 7 – Oct 9, 2025
Detected Oct 9, 2025
6 insiders
Total bought
$17.6M
Market cap
$1.8B

1 more cluster in ZBIO

All notable open-market buys in ZBIO

Every open-market Form 4 purchase, newest first. Click an insider to see their full buying record across companies.

Date	Insider	Shares	Price	Value	Filing
May 18, 2026	MOULDER LEON O JR Director, Chief Executive Officer	60,000	$16.88	$1.0M	SEC ↗
Apr 29, 2026	MOULDER LEON O JR Director, Chief Executive Officer	35,000	$17.62	$616.7K	SEC ↗
Apr 28, 2026	MOULDER LEON O JR Director, Chief Executive Officer	25,000	$18.02	$450.5K	SEC ↗
Mar 31, 2026	Fairmount Funds Management LLC Director	150,000	$20.00	$3.0M	SEC ↗
Mar 31, 2026	Lu Hongbocluster Director	75,000	$20.00	$1.5M	SEC ↗
Mar 31, 2026	MOULDER LEON O JRcluster Director, Chief Executive Officer	34,000	$19.31	$656.5K	SEC ↗
Mar 31, 2026	Lu Hongbo Director	3,768	$18.63	$70.2K	SEC ↗
Mar 30, 2026	MOULDER LEON O JRcluster Director, Chief Executive Officer	20,000	$18.23	$364.6K	SEC ↗
Feb 13, 2026	Allen Patricia Lcluster Director	4,160	$26.36	$109.7K	SEC ↗
Feb 12, 2026	Allen Patricia Lcluster Director	5,700	$24.34	$138.7K	SEC ↗
Feb 12, 2026	Allen Patricia Lcluster Director	5,000	$26.50	$132.5K	SEC ↗
Feb 12, 2026	Allen Patricia Lcluster Director	5,000	$23.77	$118.9K	SEC ↗
Feb 11, 2026	Lu Hongbocluster Director	25,985	$22.50	$584.7K	SEC ↗
Feb 2, 2026	MOULDER LEON O JRcluster Director, Chief Executive Officer	57,000	$17.96	$1.0M	SEC ↗
Jan 9, 2026	MOULDER LEON O JR Director, Chief Executive Officer	20,000	$16.55	$331.0K	SEC ↗
Jan 8, 2026	MOULDER LEON O JR Director, Chief Executive Officer	30,000	$16.30	$489.0K	SEC ↗
Jan 7, 2026	MOULDER LEON O JR Director, Chief Executive Officer	50,000	$16.38	$819.0K	SEC ↗
Oct 9, 2025	ENRIGHT PATRICK Gcluster Director	105,265	$19.00	$2.0M	SEC ↗
Oct 9, 2025	Nunn Jason Raleighcluster Director	63,158	$19.00	$1.2M	SEC ↗
Oct 9, 2025	SR ONE CAPITAL MANAGEMENT, LLCcluster 10% Owner	63,158	$19.00	$1.2M	SEC ↗
Oct 9, 2025	SR ONE CAPITAL MANAGEMENT, LLCcluster 10% Owner	63,157	$19.00	$1.2M	SEC ↗
Oct 9, 2025	ENRIGHT PATRICK Gcluster Director	11,990	$20.85	$250.0K	SEC ↗
Oct 7, 2025	Harwin Peter Evancluster Director	316,219	$19.00	$6.0M	SEC ↗
Oct 7, 2025	Lu Hongbocluster Director	263,160	$19.00	$5.0M	SEC ↗
Oct 7, 2025	MOULDER LEON O JRcluster Director, See Remarks	36,928	$20.85	$769.9K	SEC ↗

16 earlier buys hidden — sign in free to see the full history.

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ZBIO insider buying — FAQ

Are insiders buying ZBIO stock?: Yes — 11 distinct insiders have bought ZBIO (Zenas BioPharma, Inc.) on the open market, including 4 cluster buys where two or more insiders bought within a rolling window. The most recent qualifying activity was May 18, 2026.
How much ZBIO stock have insiders bought?: Insiders have bought a combined $112.9M of ZBIO across 41 open-market purchases, based on SEC Form 4 filings.
What is an insider cluster buy in ZBIO?: A cluster buy is two or more distinct Zenas BioPharma, Inc. insiders — officers, directors, or 10% owners — each buying ZBIO on the open market within a rolling window. ZBIO has 4 detected cluster buys to date.
Where does this ZBIO insider trading data come from?: Every figure is parsed directly from SEC Form 4 filings on EDGAR, and each purchase on this page links back to its original filing document.

How we track insider buying in ZBIO

We continuously poll SEC EDGAR for new Form 4 filings and parse every open-market purchase (transaction code P). A cluster is recorded when two or more distinct insiders — officers, directors, or 10% owners — each buy ZBIO within a rolling window. We track clusters at every company size, from micro-caps to mega-caps. Every figure on this page traces back to an official filing; open any row to jump straight to the source document. What counts as a cluster buy?

This page is informational and reflects public filing data. It is not investment advice or a recommendation regarding ZBIO.