Every 2026 Schedule 13D Filing, Mapped: Activists, Targets, Sectors

Executive summary. As of 2026-04-30, the 13dwatch moat database holds 148 Schedule 13D and Schedule 13D/A filings dated 2026 year-to-date. The 60 most recent — 22 initial 13Ds and 38 amendments, dated 2026-04-03 through 2026-04-28 — are listed in full below, joined to FINRA short interest, Form 4 insider activity, and elite-PM consensus. Most filings are not what the financial press calls "activism."

A Schedule 13D filing is the SEC form an investor must file within 5 business days of acquiring more than 5% of a public company's voting stock with control intent (SEC Press Release 2023-219). The colloquial "activist 13D" — Elliott, Starboard, Trian, Icahn — is a small subset of total 13D volume. The rest is founders, biotech anchor investors, corporate cross-holders, and special-situation strategics. This post is the free, web-indexable, canonical aggregated 2026 dataset that lets a reader see the distinction at a glance. It is republished quarterly. The slug stays the same; the canonical URL is permanent.

Methodology

Filings are sourced from the 13dwatch live feed, which mirrors the SEC EDGAR new-filings stream for forms SCHEDULE 13D and SCHEDULE 13D/A. Header fields (filer, issuer, share count, accession) are parsed from the structured-data XML required by the SEC since December 18, 2024. Item 4 free text and percent_owned fields are extracted by a separate parser pass and are populated for a minority of filings; where unavailable, the row shows the share count and links to the raw SEC document. Every accession number in the table below resolves to a live document on sec.gov/Archives.

Cross-source signals are joined inside the 13dwatch pipeline:

• Cluster — 2+ if the same issuer received 2 or more activist filings within a trailing 90-day window (issuer_cluster.filings_in_window >= 2).
• Insider — Y if at least one Form 4 insider purchase or disposition was filed by a corporate insider on the same issuer within the trailing 90 days.
• Consensus — Y if at least one of the 10 elite portfolio managers tracked by 13dwatch (Berkshire Hathaway, Pershing Square Capital Management, Baupost Group, Appaloosa Management, Third Point, Duquesne Family Office, Viking Global Investors, Tiger Global Management, Greenlight Capital, Lone Pine Capital) holds the issuer in their most recent 13F.

Database snapshot: 2026-04-30T06:43:58Z. Health-endpoint counts: 148 activist filings, 928 insider transactions, 11,181 institutional holdings, 171,325 short-interest records (13dwatch.com/api/health).

Headline numbers

The 60 most recent activist filings in the public-feed window:

Source: https://13dwatch.com/api/feed, snapshot 2026-04-30T06:43:58Z.

The headline finding sits in the last two rows. Roughly three-quarters of the names crossing 5% are funds, not headline activists. About one in four are individuals — founders, insiders converting to public ownership, cross-holders. The word "activist" in 13D coverage is, in any given week, doing more work than the regulatory definition supports.

Top 10 issuers by activist filing count (60-row window)

Issuers receiving multiple Schedule 13D / 13D/A filings in the trailing four weeks:

Two patterns. First, biotech dominates the multi-filer list: Alamar (Illumina + Sands Capital both crossed 5% on the same day, 2026-04-23), Kailera (Bain Capital Life Sciences Funds IV and Perseus on the same day), Achieve Life Sciences, Galera. These are syndicate financings, not boardroom campaigns. Second, the only mineable activist cluster in the window is Battalion Oil Corp (BATL) — Luminus Management's 13D/A amendment, with matching Form 4 insider activity in the trailing 90 days.

Top 10 activists by filing count (60-row window)

The colloquial "activist filer" leaderboard for the four-week window. Most names file once.

The list is short because the public window is short. The full 148-filing 2026-YTD set, queryable via the moat API, surfaces a longer leaderboard with Engaged Capital, Ancora, Trian, Icahn Enterprises, and Land & Buildings.

Sector mix

Sector classification at the corpus level requires a SIC-code lookup per issuer CIK and is gated on the next 13dwatch pipeline pass. Sector heatmap pending. From hand-reading the 60 issuer names in the public-feed window, the qualitative mix is:

• Biotech / life sciences — heaviest category (Alamar, Kailera, Achieve Life Sciences, Galera, Adicet Bio, Day One Biopharmaceuticals, Arbutus, Pulmatrix, BiomX, Neuronetics, PAVmed). These are mostly syndicate financings disclosed on 13D, not activism.
• Micro-cap / shell / penny stock — Visium, Mainz Biomed, Brera Holdings, Phunware, Banzai International. Tend to have multi-filer clusters and minimal short interest.
• Financials / community banks — Catalyst Bancorp, Equity Bancshares, First Internet Bancorp, Primis Financial Corp. Stilwell-style small-bank activism.
• Energy / mining / royalties — Battalion Oil Corp, Kimbell Royalty Partners, Nouveau Monde Graphite.
• Shipping — Genco Shipping, Diana Shipping (filer + issuer interlock).
• Consumer / media / retail — Estée Lauder (Aerin Lauder family interest), Playboy, El Pollo Loco, Truworths (ADR).
• Diversified / industrials / real estate — Compass Diversified, Service Properties Trust, Brookfield Business Corp, Boston Omaha / Sky Harbour Group, MacKenzie Realty.
• Defense / blockchain / fintech — T3 Defense filing on BiomX (PHGE — repurpose), Argo Blockchain, Mawson Infrastructure, Empery Digital, Satellogic.

The dominance of biotech and micro-cap is consistent with the academic literature (Brav, Jiang, Partnoy, Thomas 2008): activists overweight smaller, undercovered names where a 5%+ stake meaningfully shifts vote outcomes.

The full table — every activist filing in the public-feed window

Every row below is real. The Filing link column resolves to the live SGML document on sec.gov/Archives. The widget below renders the same data sortable, refreshed from /api/feed every 5 minutes.

For static reference, the snapshot taken at 2026-04-30T06:43:58Z is below. Cluster = 2+ when the issuer received 2 or more activist filings in the trailing 90 days. Insider = Form 4 insider activity in the trailing 90 days. Consensus = at least one of the 10 elite portfolio managers tracked by 13dwatch holds the name in their most recent 13F.

Sources: filings via 13dwatch.com/api/feed; cluster, insider, and consensus joins via the 13dwatch moat (activist_filings, insider_transactions, institutional_consensus); short interest via FINRA settlement-date 2026-03-31 (finra.org/finra-data/short-interest).

The full 148-filing 2026-YTD set, including the quarter before this window, is available to API-pilot subscribers via the 13dwatch PostgREST endpoint.

What this means for hedge funds and RIAs

For an emerging hedge fund manager under $500M AUM, the canonical 2026-YTD 13D table is an idea-generation feed three institutional services charge five-figures for and one (13D Monitor) keeps behind a paywall. Three operational notes.

Filter by filer type before reading anything else. Of the 60 most recent activist filings, only one is a household-name initial campaign (Two Seas Capital on Odyssey Marine, OMEX) and one is a household-name amendment (Elliott on Southwest Airlines, LUV). The other 58 are venture syndicate financings, founders' filings, individual-name filings, or institutional cross-holdings. A workflow that treats every 13D as activist will spend most of its attention on the wrong rows.

The cluster column is the second filter. Of the 7 distinct issuers with 2+ cluster status (Alamar, Kailera, Visium, Nouveau Monde Graphite, Achieve Life Sciences, Battalion Oil, Galera Therapeutics), Battalion Oil Corp is the only name where cluster status overlaps with a non-null Form 4 insider record in the trailing 90 days. The Form 4 entry on BATL shows zero open-market buys and zero sells in the window — it is a director-grant or filing-presence signal, not a cluster of insider purchases. The academic baseline (Brav, Jiang, Kim 2015) on activism + insider alignment requires actual buys; the column flags candidates, the analyst confirms.

The consensus column is the third filter. Nine filings in the window land on names where at least one of the 10 elite portfolio managers tracked by 13dwatch is already long: Achieve Life Sciences (ACHV), Primis Financial (FRST), Nouveau Monde Graphite (NMG, 2 filings), Bristow Group (VTOL), Playboy (PLBY), First Internet Bancorp (INBKZ), Chegg (CHGG), Compass Diversified (CODI-PC). Where activist filing + elite-PM holding overlap, the corroboration is what 13D Monitor does not publish for free.

For RIAs and family offices managing concentrated equity portfolios, the table answers a different question: is any portfolio holding sitting on a fresh 13D? Search by ticker. The filing landed within five business days of the underlying transaction; the analyst lag is no longer a defensible reason to be late.

Frequently asked questions

How many Schedule 13D filings have been filed in 2026?

As of 2026-04-30, the 13dwatch moat database contains 148 Schedule 13D and Schedule 13D/A filings dated 2026 year-to-date. The public live feed exposes the most recent 60 (a four-week trailing window dated 2026-04-03 through 2026-04-28). The full corpus is queryable via the API. (Source: 13dwatch.com/api/health.)

What are the biggest activist 13D filings of 2026 so far?

The largest single share-count initial Schedule 13D in the public-feed window is Lazar David E. on Mainz Biomed (QUCY) at 477,000,000 shares — a micro-cap. Among household-name activists, Elliott Investment Management filed a 13D/A amendment on Southwest Airlines (LUV) for 24,308,000 shares on 2026-04-03. Two Seas Capital filed an initial 13D on Odyssey Marine Exploration (OMEX) for 5,857,448 shares on 2026-04-13. The full canonical list is the table above.

How many distinct activist filers crossed 5% in 2026 to date?

In the public 60-filing window, 59 distinct filers crossed the 5% threshold or amended an existing filing on 56 distinct issuers. Only one filer appears twice (Canada Growth Fund Inc., on Nouveau Monde Graphite). The full 148-filing 2026-YTD set, queryable via the moat API, surfaces a longer list including Engaged Capital, Ancora, Carl Icahn, and Land & Buildings.

Which sectors are activists targeting most in 2026?

Hand-classified from the 60-row window, biotech and life sciences dominate (11 issuers including Alamar, Kailera, Achieve Life Sciences, Galera, Adicet, Day One, Arbutus, Pulmatrix, BiomX, Neuronetics, PAVmed), followed by micro-cap / shell situations (5), community banks (4), energy and mining (3), and shipping (2). A SIC-code-driven sector heatmap for the full 148-filing corpus is on the next pipeline pass and will update this section.

What is the difference between Schedule 13D and Schedule 13D/A?

Schedule 13D is the initial filing within 5 business days of crossing 5% with control intent. Schedule 13D/A is an amendment, due within 2 business days of any material change to a prior 13D. Most activism news lives in amendments — campaign letters, stake-up disclosures, response to poison pills. In the 60-filing window, 22 are initials and 38 are amendments (63% amendments). For the full taxonomy, see What Is a Schedule 13D Filing.

How is the 13dwatch dataset different from 13D Monitor or WhaleWisdom?

13D Monitor (Ken Squire) provides activist intent classification and campaign tracking on subscription. WhaleWisdom provides per-filing search across 15 years of archival data. 13dwatch joins each Schedule 13D filing to FINRA short interest, Form 4 insider transactions, and the 13F holdings of 10 elite portfolio managers in a single live feed. The cross-source join is the differentiator; the canonical free 2026 dataset above is the public showcase.

Where this fits in the 13dwatch coverage

This post is the canonical aggregated 2026 dataset. The 90-day content map is:

• What Is a Schedule 13D Filing? A Plain-English Guide With Live Examples — the prerequisite definition.
• 13D vs 13G vs 13F — the form taxonomy. (Forthcoming.)
• When 3+ Activists Circle the Same Stock — the cluster column unpacked, with case studies. (Forthcoming.)
• How to Read a Schedule 13D Purpose Section — Item 4 decoded into seven activist intent patterns. (Forthcoming.)

Live filings continue to land at 13dwatch.com. The JSON feed is at /api/feed. Pilot the joined view (activist + insider + consensus + short) for $1,500/mo — book a 20-minute call from the homepage form.

Methodology and limitations. Filing-deadline rules: SEC Press Release 2023-219, October 10, 2023; effective date for 13D, February 5, 2024. Statutory authority: Section 13(d) of the Securities Exchange Act of 1934, added by the Williams Act of 1968. Form taxonomy: Investor.gov, Schedules 13D and 13G and SEC staff Compliance and Disclosure Interpretations. Activist returns baseline: Brav, Jiang, Partnoy, Thomas (2008), Journal of Finance 63(4); Brav, Jiang, Kim (2015), Review of Financial Studies 28(10). Live filing data: 13dwatch.com/api/feed, snapshot 2026-04-30T06:43:58Z. Health-endpoint counts: 13dwatch.com/api/health, same timestamp. Short-interest joins: FINRA settlement-date 2026-03-31. The 60 filings in the public window are the most recent four weeks; the 148-filing 2026-YTD count is the moat-database total at snapshot time. SIC-code-driven sector classification of the full corpus is pending the next pipeline pass and is marked as forthcoming above. This article is research, not investment advice. Long Street Consulting LLC.