Full disclosure: Dombey Capital is our own research service and our top pick here, for the reasons below. The section on where it falls short is there so you can judge whether it fits your process.
Quick comparison
| Tool | Best for | Key features | Price (as of October 2026) |
|---|---|---|---|
| Dombey Founding MembershipTop pick | Activist stakes read as dated catalysts | Weekly Phoenix Report, Daily Phoenix Screener, Biweekly Catalyst Briefing, valuation and execution analysis | Founding Membership $1,200/year; Standard Access $80/year or $8/month |
| SEC EDGAR | Free notice of every 13D and amendment | RSS by company, CIK or form type, full-text search since 2001 | Free |
| 13D Monitor | Activist profiles and campaign research | Activist database, letters and agreements, deadline calendar, voting and standstill databases | See the vendor's site |
| Diligent Market Intelligence | Institutional campaign datasets | Searchable current and historical campaigns, global coverage, proprietary alerts | See the vendor's pricing page |
| sec-api.io | 13D data in your own code | 13D/13G API, real-time filing stream, full-text search API | 13D/13G API on Business Internal Use, $199/month; Enterprise custom |
| WhaleWisdom | Quarterly 13F holdings of activist funds | 13F history, backtester, 13D/G search, email alerts | Free; Standard $90/quarter; Pro $150/quarter; Enterprise on request |
| SECForm4.com | Free browsing of 13D and 13G filings | Live updates from EDGAR, search by company or filer | Free access; see the vendor's site for advanced tools |
| Dataroma | Free view of superinvestor portfolios | Holdings of tracked managers, top buys, insider buying in their holdings | Free |
How we compared these tools
We compared these tools from vendor documentation, pricing pages and public product pages read in October 2026, and from the SEC's rules as published in the eCFR. We did not run trials with any of them, and we make no judgment on any vendor's data accuracy or speed beyond what the vendor states.
| Criterion | Weight | What it measures |
|---|---|---|
| Catalyst context | 30% | Whether the tool helps you see what dated events follow a stake: nomination windows, meetings, votes, settlements |
| 13D notice | 25% | Whether it shows new 13Ds and amendments as they reach EDGAR, and by what channel |
| Activist history | 20% | Profiles and past campaigns, so you can judge how a given holder tends to operate |
| Path to the source | 15% | How easily you reach the filing, the exhibit letters and the company's response |
| Cost for the job | 10% | What it costs to follow activist filings across a working watchlist |
If you weight early notice above everything, EDGAR RSS and sec-api.io move up and the research products move down. If you are an adviser or a company defending against a campaign, the institutional databases move up, because their histories and voting data matter more than the price.
Quick picks by job
Best for activist stakes as dated catalysts: Dombey Founding Membership
Founding Membership is written research, not a filing feed. When an activist position bears on a special situation in Dombey's coverage, the work sets out what the holder wants, what the company can do, and the dates that decide it. Each thesis is published before its catalyst and kept in the archive.
Best free 13D notice: SEC EDGAR
An RSS feed filtered to the Schedule 13D form type shows every new filing across the market at no cost, and a company feed follows one name's amendments and exhibit letters.
Best for activist profiles and campaign research: 13D Monitor
13D Monitor is built around activism: activist profiles, a campaign database with full-text search, letters and agreements, vulnerability ratings and an activist deadline calendar.
Best institutional campaign dataset: Diligent Market Intelligence
Diligent describes searchable datasets of ongoing and historical activist campaigns with global coverage and proprietary alerts, sold through a trial and demo process.
Best for 13D data in code: sec-api.io
sec-api.io sells a 13D/13G API alongside a real-time filing stream, for people who want ownership data in their own models.
Best for 13F context on activist funds: WhaleWisdom
WhaleWisdom tracks quarterly 13F holdings with history back to 2001 on paid plans, a backtester and a 13D/G search, which helps you see what else an activist fund owns.
Best free 13D and 13G browser: SECForm4.com
SECForm4.com lists 13D and 13G filings as they reach EDGAR and lets you search past filings by company or filer, with free access.
Best free superinvestor view: Dataroma
Dataroma shows the portfolios of a set list of well-known managers, their top buys and insider buying in the stocks they hold, at no charge.
Full reviews
1. Dombey Founding Membership
What it does. Founding Membership is Dombey Capital's full research suite: the weekly Phoenix Report, weekly Options Research, the Biweekly Catalyst Briefing, and the DombeyAI Portal with the Daily Phoenix Screener and the Earnings Conviction Model, plus valuation and execution analysis and priority access. The Daily Phoenix Screener gives a view each trading morning of situations relevant to Dombey's coverage. Where an activist stake bears on a covered situation, the research reads the 13D, the exhibit letters and the company's proxy materials and turns them into a dated thesis: what the holder is asking for, what would have to happen, and by when. You can see the published work in the research archive.
Best for. Readers who follow special situations and want an activist campaign turned into a catalyst with dates and a view, not only a filing notice.
Pricing. Founding Membership is $1,200 a year, billed annually. Standard Access is the lower-cost option at $80 a year (about $6.67 a month) or $8 a month on monthly billing, and includes the Biweekly Catalyst Briefing and the complete public-research archive. The Public Archive is free.
Pros
- Interpretation of what a campaign means for value and timing, which no filing tracker provides.
- Each thesis is published before its catalyst and kept in the archive, so you can compare the case with what happened.
- Standard Access is one of the lowest-cost paid options here.
Cons
- It is not a 13D feed or an activist database; you still need EDGAR or another tool for notice.
- Coverage is limited to the situations Dombey writes about.
Verdict: Our top pick for readers who want activist stakes read as dated catalysts. Pair it with an EDGAR RSS feed for 13D notice on names outside its coverage.
2. SEC EDGAR
What it does. EDGAR is where every Schedule 13D, 13D/A and 13G is filed. The SEC's Latest Filings page lets you subscribe to all filings or filter by company, CIK or form type, and the company search lets you subscribe to one company's most recent filings. Full-text search covers electronic filings since 2001 and filters by form, date range, incorporation and principal office location. That makes it possible to search a phrase such as "strategic alternatives" across 13D filings. Our guide on how to search SEC EDGAR filings covers the filters step by step.
Best for. Anyone who wants the primary source with no cost and no filter in between.
Pricing. Free.
Pros
- Every 13D and amendment, with exhibit letters attached.
- A form-type RSS feed covers the whole market in one subscription.
- Full-text search across filings since 2001.
Cons
- The SEC states that its email update service is not available for company filings, so alerts mean RSS or a third-party tool.
- No activist profiles, campaign histories or interpretation.
Verdict: Essential and free. Set up the form-type feed before paying for anything else.
3. 13D Monitor
What it does. 13D Monitor is an activism research service. Its site lists an activist database with ticker search, activist profiles (active, other, inactive and international filers) and a campaign database with general and full-text search. It also lists activist letters and agreements, M&A activism, activism vulnerability ratings, The Activist Report, weekly and monthly filings, tear sheets, a board representation and standstill database, a voting database, proxy commentary and an activist deadline calendar. It offers separate US and international activism subscriptions.
Best for. Investors and advisers who want a dedicated activism research product with campaign history and deadlines in one place.
Pricing. No price is listed; the site offers subscription and demo requests. See the vendor's site.
Pros
- Built only around activism, with profiles, campaigns and letters together.
- A deadline calendar and voting and standstill databases address the dates that decide a campaign.
- International coverage is offered as a separate product.
Cons
- No published price, so budget is unknown until you contact the vendor.
- The home page does not describe alerts.
Verdict: The most activism-specific research product here for readers who want campaign depth.
4. Diligent Market Intelligence
What it does. Diligent's Market Intelligence product describes searchable datasets of ongoing and historical activist campaigns, global coverage of activist investors and campaigns, and proprietary alerts to spot activists quickly. Diligent also publishes research reports, such as its Shareholder Activism Review 2026.
Best for. Companies, advisers and institutions that need a campaign dataset for governance and defense work.
Pricing. Not listed; the page offers a free trial request and a demo. See the vendor's pricing page.
Pros
- Current and historical campaigns in searchable datasets.
- Global coverage and alerts described by the vendor.
Cons
- No published price, and the sales process suits institutions more than individuals.
- Built for governance teams as much as investors, so much of the product may not apply to an individual's watchlist.
Verdict: A strong fit for institutions; individuals will usually get enough from EDGAR plus research.
5. sec-api.io
What it does. sec-api.io turns EDGAR into APIs: a real-time filing stream, full-text search, parsed insider and institutional holdings data, and a 13D/13G API that returns ownership filings as structured data.
Best for. Developers and quantitative researchers who want 13D data in their own screens or models.
Pricing. Free with 100 API calls in total. Personal and Startups is $49 a month ($588 billed yearly) and does not include the 13D/13G API in the vendor's comparison table. Business Internal Use is $199 a month ($2,388 billed yearly) and includes it. Enterprise and Institutions is custom.
Pros
- Structured 13D data you would otherwise parse from EDGAR yourself.
- The same vendor offers the real-time stream, so notice and data come from one source.
Cons
- You need to write code.
- The 13D/13G API sits on the $199 tier, which is expensive for occasional use.
Verdict: The developer's choice for 13D data at scale.
6. WhaleWisdom
What it does. WhaleWisdom is a 13F tracker. Its pricing page lists a free plan with two years of 13F data, unlimited email alerts and a backtester, and paid plans with historical 13F data back to 2001 through the API, watchlists and a dashboard search. The Standard plan notes that export is not available for 13D/G search, and Enterprise adds nightly FTP files for 13F and Schedule 13D/G.
Best for. Readers who want to see what an activist fund holds across its portfolio, quarter by quarter.
Pricing. Free plan. Standard $90 a quarter. Pro $150 a quarter. Enterprise on request.
Pros
- Long 13F history and a backtester for manager portfolios.
- A useful free plan with email alerts.
Cons
- 13F reports are filed within 45 days after each quarter ends, so they show where a fund was, not what it is doing now.
- 13F shows positions, not intent; Item 4 of a 13D does that.
Verdict: Good context on an activist's wider book; pair it with EDGAR for timely 13D notice.
7. SECForm4.com
What it does. SECForm4.com describes its 13D and 13G coverage as live updates directly from SEC EDGAR, with tools to spot new holders above 5%, follow activist and hedge fund activity, and search historical 13D and 13G records by company or filer. It also tracks Form 4 insider filings.
Best for. A free, browsable list of new ownership filings next to insider trades. Our list of the best tools for tracking insider buying covers the insider side in more detail.
Pricing. The site describes free access with advanced tools for power users. See the vendor's site for any paid tools.
Pros
- Free and focused on ownership filings.
- Insider purchases and 5% holders in one place, which helps when both point the same way.
Cons
- The page we read did not describe alerts.
- No campaign history or interpretation.
Verdict: A convenient free browser for 13D and 13G filings.
8. Dataroma
What it does. Dataroma tracks the portfolios of a fixed list of superinvestors, 83 at the time we read it, with each manager's last update date, the most-owned stocks, top buys over recent quarters, holdings near 52-week lows and a feed of insider purchases in those holdings.
Best for. A free, quick look at what well-known value managers hold, some of whom run activist campaigns.
Pricing. Free; no pricing appears on the site.
Pros
- Free and easy to scan.
- Aggregate views such as top buys across managers.
Cons
- The home page lists no 13D or activist-specific pages.
- A fixed manager list, so most activist funds may not appear.
Verdict: A free second look at manager portfolios, not an activist tracker on its own.
Where Dombey falls short
Founding Membership does one part of this job, and its limits are real:
- Narrow coverage. It covers special situations in Dombey's research coverage. A 13D at a company outside that coverage will not appear in the research.
- Not a filing tracker or database. There is no 13D feed, alert system, activist profile database or API. Use EDGAR or one of the tools above for those.
- Small team and pen-name author. The research is written by a small team, and the byline is a pen name. Read the 13D and the company's response yourself before acting on any summary.
- Short history. The publication's record is short next to activism databases that have run for many years.
Free vs paid
Free tools cover notice. An EDGAR RSS feed on the Schedule 13D form type shows every new filing, a company feed follows amendments, and full-text search finds language such as "nominate" or "sale of the company" across filings. SECForm4.com and Dataroma add easier browsing, and WhaleWisdom's free plan adds 13F history and alerts.
Paid tools buy one of three things: campaign history and deadlines (13D Monitor, Diligent Market Intelligence), structured data (sec-api.io, WhaleWisdom's paid plans), or interpretation. Founding Membership buys interpretation of activist campaigns as dated catalysts, with Standard Access as the lower-cost option for the Catalyst Briefing and archive.
How to choose
Start with what you need to know about the campaign, then pick the cheapest tool that answers it.
| Your situation | Pick | Add later when |
|---|---|---|
| You want activist stakes read as dated catalysts | Dombey Founding MembershipTop pick | You need notice on names outside its coverage: add EDGAR RSS |
| You want free notice of every new 13D | SEC EDGAR | You want activist histories: add 13D Monitor |
| You advise companies or follow campaigns full time | 13D Monitor or Diligent Market Intelligence | You want a written view on value: add Dombey Founding Membership, or Standard Access as the lower-cost option |
| You build screens or models in code | sec-api.io | You only need a few names: drop to EDGAR RSS |
| You want to see what activist funds hold | WhaleWisdom | You need current intent: read the 13D on EDGAR |
| You want a free browsable list | SECForm4.com | You want alerts: use EDGAR RSS in a feed reader |
- If a 13D names board seats, put the nomination deadline and the annual meeting date on your catalyst calendar.
- If the company files a definitive proxy for a contested meeting, read both sides; our guide on how to read a proxy statement shows where the terms sit.
- If the activist asks for a sale or a break-up, the value case often rests on the parts; see holding company discounts.
- If you want alerts on other forms too, see the best SEC filing tools and EDGAR alerts.
The bottom line
Dombey's Founding Membership is our top pick for readers who want activist stakes read as dated catalysts, with Standard Access as the lower-cost option. It is not a tracker, so pair it with SEC EDGAR, which is free and carries every 13D and amendment. For campaign histories and deadlines, use 13D Monitor or Diligent Market Intelligence; for 13D data in code, sec-api.io; and for quarterly holdings, WhaleWisdom. Whatever you use, read Item 4 and the exhibit letters yourself, because the filing states what the holder wants and the dates that follow decide whether it gets it.