Insider Radar — Week of September 28, 2026
Reported insider buying was $673.5 million in the week of September 28 and selling was $2.10 billion, a ratio of 3.1 to 1 against a median of 11.7 over the preceding twenty-six weeks. Berkshire Hathaway added $246.5 million of Lennar in its third straight week of filings, and Baker Bros. Advisors bought $157.0 million of Kodiak Sciences in the week the company reported Phase 3 results. Three sponsor sales, at Accelevation Holdings, Medline and Target Hospitality, made up 43% of the selling. Activity picked up, with 808 filings against 564 the week before.
Insiders sold $2.10 billion and bought $673.5 million in the week of September 28, a ratio of 3.1 to 1 against a recent median of 11.7 and the most buy-heavy week since late August. Four large holders supplied 79% of the buying, led by Berkshire Hathaway in Lennar and Baker Bros. in Kodiak Sciences. Ordinary open-market purchases by officers and directors came to about $70 million.
Four large holders supplied most of the buying
Reported buying came to $673.5M across 238 events, 2.6 times the $255.5M median of the preceding twenty-six weeks. Four 10% holders account for $531.7M of it, 79%: Berkshire Hathaway in Lennar, Baker Bros. Advisors in Kodiak Sciences, Conifer Management in Group 1 Automotive and Nippon Life in Corebridge Financial. Officers and directors filing in their own names bought $102.4M across 171 events. Take out the offering purchases described at the end of this section and about $70M of that is ordinary open-market buying.
Lennar (LEN) is the largest line for the third week running. Berkshire Hathaway bought on all five sessions from September 28 to October 2: $245.0M of Class A at $78.37–$81.96 and $1.5M of Class B at $77.12–$80.00. After the last purchase it reported 28,438,045 Class A shares. With the two earlier weeks, the reported total since it crossed the 10% threshold is $595.3M. The filings are made in the indirect form, through Berkshire subsidiaries.
Baker Bros. Advisors, which files at Kodiak Sciences (KOD) as both a director and a 10% holder, bought $154.1M on September 28 at prices from $61.21 to $89.86 and another $2.9M on September 29, $157.0M in all. The company reported Phase 3 results for its wet age-related macular degeneration treatments that week, and the spread of prices within one session shows how far the stock moved while the funds were buying. This is a large existing holder adding after a binary event, which is a different signal from a manager buying their own company's stock.
Conifer Management bought $66.3M of Group 1 Automotive (GPI) from September 28 to September 30 at $235.63–$250.35, its fifth consecutive week of additions. Nippon Life added $62.0M of Corebridge Financial (CRBD) across five sessions at $32.78–$34.76, its fourth straight week, and its filings mark these purchases as made under a 10b5-1 plan.
The individual buying is led by GameStop (GME). President, CEO and chairman Ryan Cohen bought 450,000 shares at $23.45–$23.48 on September 29 and 700,000 at $24.4061 on October 2, $27.6M in all, and reported 41,648,522 shares afterwards. Director Nat Turner added $0.3M at $24.33. Bluerock Private Real Estate Fund (BPRE) director Ramin Kamfar bought $7.6M across five sessions at $12.50–$12.69, and Pampa Energy (PAM) vice president Damian Mindlin bought $5.6M of shares and ADSs on September 28. Nayax (NYAX) chief executive Yair Nechmad bought $4.2M over three sessions at $44.51–$48.56. Oracle (ORCL) director Stephen H. Rusckowski bought 25,000 shares at $139.352 on September 29, $3.5M. Pershing Square USA (PSUS) chief investment officer Ryan Israel bought $2.9M at $37.2092, Kayne Anderson BDC (KBDC) director James L. Robo $1.9M at $13.0330, and at Xenon Pharmaceuticals (XENE) president and CEO Ian Mortimer and chief financial officer Thomas Kelly bought $1.7M between them on September 30 at $37.32–$37.38.
Two sets of purchases are financing, and they are named so they are not read as conviction. Existing holders of ADARx Pharmaceuticals (ADRX) bought $44.4M of stock at $17.00 on September 28: $27.2M by SR One Capital Management, reported jointly with director George Simeon, $16.2M by OrbiMed Advisors, reported jointly with Carl L. Gordon and marked on the filing as a public offering, and $1.0M reported by director Erez Chimovits. At Accelevation Holdings (ACCV), chief executive Michael Rubiera and four other officers and directors bought $4.1M at the $18.00 public offering price on October 1.
| Ticker | Buyer | Role | Value | Price | Date |
|---|---|---|---|---|---|
| LEN | Berkshire Hathaway Inc | 10% holder, Class A | $245.0M | $78.37–$81.96 | Sep 28–Oct 2 |
| KOD | Baker Bros. Advisors LP | Director and 10% holder | $157.0M | $61.21–$89.86 | Sep 28–29 |
| GPI | Conifer Management, L.L.C. | 10% holder | $66.3M | $235.63–$250.35 | Sep 28–30 |
| CRBD | Nippon Life Insurance Co | 10% holder, 10b5-1 | $62.0M | $32.78–$34.76 | Sep 28–Oct 2 |
| GME | Ryan Cohen | President, CEO and Chairman | $27.6M | $23.45–$24.41 | Sep 29, Oct 2 |
| ADRX | SR One Capital Management / George Simeon | Director and 10% holder (financing) | $27.2M | $17.00 | Sep 28 |
| ADRX | OrbiMed Advisors LLC | Director and 10% holder (public offering) | $16.2M | $17.00 | Sep 28 |
| BPRE | Ramin Kamfar | Director | $7.6M | $12.50–$12.69 | Sep 28–Oct 2 |
| PAM | Damian Mindlin | Vice President (shares and ADSs) | $5.6M | $3.105 / $77.628 per ADS | Sep 28 |
| NYAX | Yair Nechmad | CEO, Co-Founder and Chairman | $4.2M | $44.51–$48.56 | Sep 28–30 |
| ACCV | Michael Rubiera | Chief Executive Officer (public offering) | $3.7M | $18.00 | Oct 1 |
| ORCL | Stephen H. Rusckowski | Director | $3.5M | $139.352 | Sep 29 |
| PSUS | Ryan Israel | Chief Investment Officer | $2.9M | $37.2092 | Oct 2 |
| KBDC | James L. Robo | Director | $1.9M | $13.0330 | Sep 28 |
| LEN | Berkshire Hathaway Inc | 10% holder, Class B | $1.5M | $77.12–$80.00 | Sep 29–Oct 2 |
| XENE | Ian Mortimer | President and CEO | $1.1M | $37.38 | Sep 30 |
Three sponsor sales were 43% of the selling
Insiders and large holders sold $2.10B across 677 events. Against $673.5M of buying that is 3.1 to 1, below the 11.7 median of the twenty-six preceding weeks and the lowest reading since the week of August 24. The middle half of those weeks sat between 5.4 and 22.4 and the full range runs from 0.9 to 42.2. The selling itself was not unusual: $2.10B is below the $2.75B weekly median, so the low ratio comes from the buying side.
Of the selling, $902.9M, 43%, was under 10b5-1 plans. Another $49.6M was D-code disposals back to issuers, and $44.8M of that is Roivant Sciences returning 8,967,383 Arbutus Biopharma (ABUS) shares to the company at $5.00 on October 1; it still holds 29,880,079. The remaining $1,142.9M was open-market selling outside any plan, and $898.6M of that is three sponsor sales.
OGP VIII sold 20,000,000 Accelevation Holdings (ACCV) shares at $18.00 on October 1, $360.0M, the same price at which the company's officers and directors bought in its offering that day, and still reports 90,022,472 shares. GIC sold 9,717,940 Medline (MDLN) shares on October 2, 7,146,941 at $34.33 and 2,570,999 at $35.35, $336.2M in all. TDR Capital sold 11,000,000 Target Hospitality (TH) shares at $18.40 on October 1, $202.4M, and holds 16,226,363 afterwards. Separately, Genworth Holdings sold $37.1M of Enact Holdings (ACT) at $48.6528 and still holds 109,628,073 shares.
The scheduled sales were concentrated in technology. Cerebras Systems (CBRS) chief operating officer Dhiraj Mallick sold $80.8M on September 29 at $194.91–$212.93, part of $87.7M of plan sales at the company. CrowdStrike (CRWD) insiders sold $98.2M, all under plans, led by president Michael Sentonas at $64.2M. At Apple (AAPL), executive chair Tim Cook sold $63.8M at $331.44–$333.94 on October 2, within $88.6M of plan sales by four insiders. Monolithic Power Systems (MPWR) chief executive Michael Hsing sold $40.3M, CoreWeave (CRWV) chief executive Michael Intrator $26.7M, and Lumentum (LITE) chief financial officer Wajid Ali $25.7M at $1,048.50, all under plans.
Outside plans, the largest individual sales were Medpace (MEDP) president and CEO August J. Troendle, $31.8M across three sessions at $620.07–$625.47 after $71.9M the week before, and Berkshire Hathaway (BRK-A) vice chairman Ajit Jain, who sold 39,700 Class B shares at $503.0926 on September 28, $20.0M. Intrator also sold $6.9M of CoreWeave outside his plan on September 30, at the same $87.69 as sales by four other executives that day.
| Ticker | Seller | Role | Value | Type | Date |
|---|---|---|---|---|---|
| ACCV | OGP VIII, LLC | 10% holder | $360.0M | Sale at the $18.00 offering price | Oct 1 |
| MDLN | GIC Private Ltd | 10% holder | $336.2M | Blocks at $34.33 and $35.35 | Oct 2 |
| TH | TDR Capital II Investments LP | 10% holder | $202.4M | Block at $18.40 | Oct 1 |
| CRWD | CrowdStrike insiders (4) | Officers | $98.2M | 10b5-1 | Sep 28–Oct 2 |
| CBRS | Dhiraj Mallick | Chief Operating Officer | $80.8M | 10b5-1 | Sep 29 |
| AAPL | Tim Cook | Executive Chair | $63.8M | 10b5-1 | Oct 2 |
| ABUS | Roivant Sciences Ltd. | Director and 10% holder | $44.8M | D-code disposal to issuer | Oct 1 |
| MPWR | Michael Hsing | Chief Executive Officer | $40.3M | 10b5-1 | Sep 28 |
| ACT | Genworth Holdings, Inc. | 10% holder | $37.1M | Open market, no plan | Sep 30 |
| MEDP | August J. Troendle | President and CEO | $31.8M | Open market, no plan | Sep 28–30 |
| CRWV | Michael Intrator | CEO and President | $26.7M | 10b5-1 | Sep 29 |
| LITE | Wajid Ali | EVP and Chief Financial Officer | $25.7M | 10b5-1 | Oct 1 |
| BRK-A | Ajit Jain | Vice Chairman, Class B shares | $20.0M | Open market, no plan | Sep 28 |
Methodology
Source data is public SEC Form 4 filings collected by AlphAI, covering transactions dated September 28 through October 4, 2026: 808 filings with a reported value, and 793 filings across 466 tickers after the exclusions below. Transactions are grouped into events by ticker, filing, ownership form, transaction code and date, so a sale executed in many tranches under one filing counts once rather than inflating the count. Purchases are P-code transactions, disposals are S and D codes. Event groups summing above $1 billion are excluded, because at that size the row is almost always a merger, tender or reorganisation rather than a discretionary trade; this week the cap removed nothing. Where several related filers report the same block, only one copy is counted: filings are collapsed when the ticker, date, transaction code, security title, share count and value all match, keeping the direct filer's copy where there is one. That correction removed $53.2 million of sales and $43.4 million of buys across 23 groups, the largest being an $11.1 million Bumble (BMBL) sale reported by five Blackstone entities, and the two ADARx Pharmaceuticals (ADRX) purchases at $17.00: $27.2 million reported by both SR One Capital Management and George Simeon, and $16.2 million reported by both OrbiMed Advisors and Carl L. Gordon. One residual copy remains: Erez Chimovits's $1.0 million ADARx purchase repeats an OrbiMed tranche but is reported as a separate block and is not collapsed. Five items are excluded from both sides because the recorded dollar figure does not describe an open-market trade. MineralRite (RITE), an OTC issuer: a $106.7 million sale of 3,919,388 Series NMC Preferred shares at $27.23. DigitalBridge (DBRG): twelve D-code dispositions at a flat $16.00 on September 30, $67.4 million in all, which is the cash consideration in SoftBank's acquisition of the company, completed that day. Hyperscale Data (GPUS): a $5.1 million event in which 10,000,000 shares are reported at $0.50 while the same filers' other purchases those days were at $0.16 to $0.17. SL Science (SLBT): 4,545,306 shares at a flat $0.50 by its chief executive, $2.3 million, which has the shape of a placement rather than a market trade. Banco Bradesco (BBD): $1.0 million of preference shares priced in Brazilian reais while the data records US dollars. Together they remove $174.2 million of sales and $8.3 million of buys; with them included the ratio would read 3.3 to 1 rather than 3.1. Activity filed under 10b5-1 plans is split out, because those trades are scheduled months ahead and say nothing about what a seller thinks now. D-code disposals back to an issuer are reported separately from open-market selling. Roles come from the officer, director and 10 percent holder flags on the filing itself, and titles are used only where the filing supplies one. The recent median sell to buy ratio covers the twenty-six preceding weeks that each had more than $10 million of reported buying, and those weeks ranged from 0.9 to 42.2, so a single week's ratio should be read against that spread rather than on its own. Filing coverage matured over the first half of 2026, so week to week comparisons are more reliable than comparisons with the spring. This is a readout of public filings and not investment advice.
Sources: SEC EDGAR Form 4 filings
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