The 13dwatch Activist+Insider Index: Q2 2026 Edition

Executive summary. The 13dwatch Activist+Insider Index screens every Q2 2026 Schedule 13D/13G filing against the issuer's own Form 4 open-market purchases. Thirteen issuers overlap, but nine are financing artifacts — IPO placements, non-traded-fund subscriptions, and SPAC sponsor shares. Only GeneDx, where director Eli Casdin's funds bought roughly $21 million on the open market, is a clean activist-plus-insider conviction signal.

Short answer. When you cross-reference every 5%-plus beneficial-owner filing against the target company's own insider purchases for the second quarter of 2026, the dollar-ranked list is almost entirely noise. Strip out the structural flows — initial public offering placements, non-traded fund net-asset-value subscriptions, special-purpose acquisition company (SPAC) sponsor mechanics, and one negotiated margin-loan block — and a single issuer survives as a textbook case of an activist-class filer buying alongside a sitting director on the open market: GeneDx Holdings (Nasdaq: WGS).

Methodology

This index is built from two live 13dwatch endpoints, with no modeled or estimated values. The overlap set comes from the /api/admin/insider-overlap-study endpoint, which joins the full activist_filings table — 18,537 Schedule 13D and 13G filings spanning January 2, 2018 through June 22, 2026 — to the insider_transactions table on the issuer's Central Index Key (CIK), within a plus-or-minus 90-day window, and counts only transaction-code-P ("open market or private purchase") rows on insiders who are not the activist filer itself. Database row counts were read from the live /api/health endpoint on June 23, 2026. The quarter is defined by filing date, April 1 through June 22, 2026. Candidates were deduplicated by issuer and ranked by code-P dollar volume; each was then classified by hand using the underlying Form 4 rows. Every genuine-signal figure was re-verified against the original filing in the U.S. Securities and Exchange Commission (SEC) EDGAR system.

What "code P" actually captures — and why the raw list misleads

The SEC defines Form 4 transaction code P as an "open market or private purchase of a non-derivative or derivative security" (SEC Form 4 instructions). That single code is the best Form 4 proxy for conviction buying. It is also the source of the problem: because code P covers private purchases as well as open-market ones, it sweeps in initial public offering allocations, private placements, fund subscriptions, and negotiated block trades — none of which carry the signal that an insider is voluntarily paying the market price for more of their own stock.

A Schedule 13D signals control intent; a Schedule 13G signals a passive or institutional position. Pairing either with code-P insider buying should, in theory, surface the highest-conviction setups on the tape. In practice, the dollar-weighted ranking is dominated by issuers where both the 5%-plus filing and the "insider purchase" are mechanical consequences of the same financing event.

The Q2 2026 screen

Thirteen unique issuers in the second quarter of 2026 show a Schedule 13D or 13G filer overlapping with non-self code-P insider purchases inside the window. Ranked by raw code-P dollars, with the mechanism classified from the underlying Form 4 rows:

Source: 13dwatch /api/admin/insider-overlap-study, window ±90 days, run 2026-06-23. Mechanism classified from underlying Form 4 rows. "Genuine" = open-market purchase by a company officer or director at dispersed prices, distinct from a placement, subscription, or negotiated block.

Numbered findings

1. Nine of the top thirteen are financing artifacts. Four biotech names (Kailera, Odyssey, Seaport, Alamar) are IPO or crossover placements where venture funds "purchased" at a single uniform price on a single date. Three (Blackstone Digital Infrastructure, Audax Private Credit, EagleRock Land) are non-traded funds where "insider buying" is a net-asset-value subscription at a flat price. One (BurTech) is SPAC sponsor mechanics. None reflect open-market conviction.

1. The dollar ranking is actively misleading. Kailera tops the list at $326.8 million and is the least informative entry — a Schedule 13D filed by a venture sponsor at the moment its portfolio company went public. Raw code-P dollars reward size, and the largest code-P events of the quarter were financings.

1. GeneDx (WGS) is the one clean signal. Funds affiliated with Casdin Capital — whose principal, Eli Casdin, is a GeneDx director and a Schedule 13D filer — bought 500,000 Class A shares on May 18–20, 2026 across three days at dispersed prices of $42.55, $42.60, and $43.81, totaling roughly $21.4 million. They added about $11.1 million more on June 4–5 at $52.86 to $56.44 (The Motley Fool, June 11, 2026). Multi-day, price-dispersed buying by a board member who is also a 5%-plus filer is the pattern the index is built to find.

1. Black Rock Coffee Bar (BRCB) is genuine but confounded — and far smaller than it looks. The $73.4 million raw figure is dominated by negotiated code-P acquisitions by Cynosure Group, not open-market buying: on May 15, 2026, Viking Cake sold roughly 7.8 million units to Cynosure Partners III for $41.7 million to repay a margin loan, after which Viking Cake reported zero beneficial ownership (StockTitan BRCB filings). The genuine open-market component is only about $369,000 — small officer buys by the principal accounting officer ($49,558 at $6.98 on May 20), the chief operating officer, and the chief marketing officer. The interesting story is officers buying small while the large 13D holder force-sold; the headline dollar figure is not conviction.

1. Hemab is fund accumulation, not company insider buying. RA Capital Management bought across multiple May–June dates at dispersed prices ($24.89–$25.00), which is real open-market activity — but RA Capital is a crossover investor, not an officer or director of the company. It is a fund building a position, not management backing its own equity.

1. Aurinia is a single-principal overlap. Tang Capital Management filed the Schedule 13D/A, and Kevin Tang — Tang Capital's principal — is Aurinia's chief executive. His ~$12.5 million of buying is real, but the "activist" and the "insider" are the same person; there is no independent second party confirming the thesis.

1. The congressional leg is empty this quarter. Extending the screen to a third factor — overlapping congressional purchase disclosures — yields zero Q2 2026 clusters and only three in the entire 2018–2026 history. Three-factor activist-plus-insider-plus-Congress clusters are vanishingly rare; this quarter produced none.

1. The base rate stays low. Across the full universe, only 233 of 18,537 filings (1.26%) sit within 90 days of a non-self code-P insider purchase. That is consistent with prior 13dwatch cluster work — see the 2018–2026 cluster study and why cluster buys beat single buys. Genuine, independent activist-plus-insider conviction is rare by construction, which is exactly why a quarter that surfaces even one clean case is worth cataloguing.

What this means for emerging managers and RIAs

The lesson of the Q2 2026 index is that the screen is easy and the filter is hard. Any vendor can join 5%-plus filings to Form 4 code-P rows and print a list ranked by dollars; that list will be topped by IPO placements and fund subscriptions every quarter. The work that produces signal is the classification step — reading the underlying Form 4 rows to separate open-market conviction from financing plumbing, and separating an independent insider's buying from the activist filing its own purchases. For a fund under $500 million in assets without a data team, that filtering is the expensive part, and it is where the 13dwatch feed and the historical filing map are designed to do the work. The one name that clears the filter this quarter — GeneDx — is the kind of independent, multi-day, board-level open-market buy that the original activist-while-insider study flagged as the highest-conviction configuration.

Frequently asked questions

What is the 13dwatch Activist+Insider Index?

It is a quarterly screen that cross-references every Schedule 13D and 13G beneficial-ownership filing against the target issuer's own Form 4 insider open-market purchases (transaction code P) within a 90-day window, then classifies each overlap to separate genuine conviction buying from financing artifacts. The Q2 2026 edition covers filings from April 1 to June 22, 2026.

What did the Q2 2026 index find?

Thirteen issuers showed an activist-class filing overlapping with non-self code-P insider purchases. Nine of the top thirteen were financing artifacts — biotech IPO placements, non-traded fund subscriptions, or SPAC sponsor shares. GeneDx (WGS) was the single clean case of a Schedule 13D filer buying alongside an independent director on the open market.

Why is GeneDx the standout?

Casdin Capital, whose principal Eli Casdin is a GeneDx director and Schedule 13D filer, bought 500,000 shares over three days in May 2026 at dispersed open-market prices (about $21.4 million), then added roughly $11.1 million more in early June. Multi-day, price-dispersed buying by a board member who is also a 5%-plus filer is independent, repeated conviction — not a one-time placement.

Why exclude the biotech names with the largest dollar figures?

In names like Kailera, Odyssey, Seaport, and Alamar, the "code-P purchases" occurred at a single uniform price on a single date — the signature of an IPO allocation or private placement, not open-market accumulation. They top the dollar ranking precisely because financings are large, which is why dollar rank alone is misleading.

Is transaction code P always open-market buying?

No. The SEC defines code P as an "open market or private purchase," so it also captures private placements, fund subscriptions, and negotiated block trades. Distinguishing genuine open-market buying requires reading the underlying Form 4 rows for price dispersion and buyer identity, which is the core of this index's classification step.

How often do activist filings overlap with insider buying?

Rarely. Across the full 2018–2026 universe of 18,537 filings, only 1.26% sit within 90 days of a non-self code-P insider purchase. Adding a third factor — congressional purchases — produced zero overlaps in Q2 2026 and only three in eight years.

Methodology and limitations

Data was read live on June 23, 2026 from the 13dwatch /api/admin/insider-overlap-study endpoint (window ±90 days) and the /api/health endpoint. The activist set is the full activist_filings table (18,537 rows, 2018-01-02 to 2026-06-22). The insider join sampled 50,000 of 87,331 insider_transactions rows; low-dollar tail rankings could shift outside that sample, though the top-by-dollars candidates are unlikely to move. GeneDx's June 4–5 purchases fall outside the May 13D/A window in the study row and are sourced from EDGAR and contemporaneous press, not from the study itself. One insider row in the broader table carries an out-of-range future date, a known parser artifact; it does not fall in the Q2 window and does not affect any figure above. Short-interest enrichment was available only for the most recent weekly filing window and was therefore not applied across the full quarter. Primary sources: SEC EDGAR full-text search; SEC Form 4 instructions; SEC Schedule 13D/13G guidance; GeneDx Schedule 13D/A, EDGAR; The Motley Fool, June 11, 2026; StockTitan BRCB filings.

This is research, not investment advice. Nothing here is a recommendation to buy or sell any security. Data is presented as filed and may contain reporting or parsing errors. © 2026 Long Street Consulting LLC.

Get the live feed of activist filings cross-referenced with insider buying from 13dwatch — $1,500/month, or book a 20-minute call.