Quantisnow Insider Buying Index
Insider buying in September 2026
Last updated . Recomputed daily.
In September 2026, insiders bought $1.98B of stock in open-market purchases across 408 companies, up 39.7% from August, against $13.49B of open-market sales, based on 939 Form 4 purchase filings.
Key figures
- Insider purchase value
- $1.98B
- Prior month: $1.42B
- Insider purchase filings
- 939
- Prior month: 1,116
- Companies with insider buying
- 408
- Prior month: 506
- Cluster buys (3+ filings)
- 111
- Prior month: 122
- Insider open-market sale value
- $13.49B
- Prior month: $19.89B
- Buy-to-sell value ratio
- 0.15
- Prior month: 0.07
- All Form 4 filings
- 9,831
- Prior month: 11,684
Companies with the largest insider purchases, September 2026
| Company | Purchase value | Filings |
|---|---|---|
| Republic Services Inc. (RSG) | $576.0M | 4 |
| Berkshire Hathaway Inc. (BRK.B) | $402.7M | 3 |
| Kodiak Sciences Inc (KOD) | $157.0M | 3 |
| Corebridge Financial Inc. (CRBD) | $123.8M | 14 |
| Group 1 Automotive Inc. (GPI) | $121.0M | 5 |
| GameStop Corporation (GME) | $59.1M | 7 |
| QVC, Inc. (QVCC) | $39.0M | 3 |
| Flotek Industries Inc. (FTK) | $34.3M | 1 |
| PAMT CORP (PAMT) | $31.2M | 1 |
| Grab Holdings Limited (GRAB) | $30.7M | 2 |
| Globalstar Inc. (GSAT) | $29.8M | 1 |
| Banco Bradesco Sa (BBDO) | $28.0M | 22 |
| Aura Minerals Inc. (AUGO) | $21.8M | 3 |
| Uber Technologies Inc. (UBER) | $15.3M | 2 |
| CapsoVision Inc. (CV) | $15.0M | 2 |
| Liberty Latin America Ltd. (LILAK) | $12.2M | 4 |
| CPI Card Group Inc. (PMTS) | $12.0M | 5 |
| Coursera Inc. (COUR) | $11.4M | 1 |
| Alumis Inc. (ALMS) | $10.7M | 1 |
| Fox Corporation (FOXA) | $10.3M | 1 |
| Kayne Anderson BDC Inc. (KBDC) | $10.0M | 4 |
| Cybin Inc. (HELP) | $9.6M | 8 |
| Greenwave Technology Solutions Inc. (GWAV) | $8.0M | 1 |
| AXIA Energia (AXIA) | $7.3M | 3 |
| A Paradise Acquisition Corp. (APAD) | $7.3M | 2 |
Methodology
An insider purchase is a Form 4 filed with the SEC whose non-derivative table reports an open-market purchase (transaction code P) by an officer, director or 10% owner. Quantisnow parses every Form 4 from EDGAR as it is accepted, computes the dollar value of each transaction (shares times reported price), and tags filings with a purchase as the Insider Buy category.
Purchase value sums those reported dollar values across all purchase filings in the month. Sale value does the same for open-market sales (transaction code S) on every other Form 4, so tax withholding, option exercises, grants and gifts are excluded from both sides. Transactions reported without a price carry no dollar value. Amended Form 4s (4/A) are excluded because they restate a filing already counted, and transactions priced above $10,000 per share or worth more than $2 billion are excluded as reporting errors (typically a price filed in cents or a foreign currency). A filing whose purchases exceed twice the company's current market capitalization is also excluded from value (usually an issuer reporting its own share issuance).
Companies counts distinct issuers with at least one purchase filing. A cluster buy is an issuer with three or more purchase filings in the same month, a common proxy for several insiders buying together.
Figures are recomputed daily from the Quantisnow event database. The current month is marked as month to date until it closes; closed months are recomputed for a few days after month end to pick up late filings, then stay fixed.
April 2026: Insider purchase tagging was interrupted for part of this month, so purchase counts and values are incomplete. Form 4 totals are unaffected.
October 2026: Insider purchase tagging was interrupted for part of this month, so purchase counts and values are incomplete. Form 4 totals are unaffected.
Definitions for every column are in the JSON download.
Metric definitions
- Insider purchase value
- (
buyValue): Dollar value of open-market purchases (transaction code P) reported on Form 4. - Insider purchase filings
- (
buys): Form 4 filings reporting at least one open-market purchase. - Companies with insider buying
- (
companies) - Cluster buys (3+ filings)
- (
clusters): Companies with three or more insider purchase filings in the month. - Insider open-market sale value
- (
sellValue): Dollar value of open-market sales (transaction code S) reported on Form 4. - Buy-to-sell value ratio
- (
buySellRatio): Purchase value divided by open-market sale value. - All Form 4 filings
- (
form4)
Download and cite
Free to reuse under CC BY 4.0 with attribution to Quantisnow and a link to this page.
Quantisnow. (2026). Quantisnow Insider Buying Index, September 2026 [Data set]. Retrieved October 30, 2026, from https://www.quantisnow.com/data/insider-buying/2026-09
<figure style="margin:0;max-width:720px"><a href="https://www.quantisnow.com/data/insider-buying"><img src="https://www.quantisnow.com/data/insider-buying.svg" alt="Quantisnow Insider Buying Index chart" width="720" height="340" style="width:100%;height:auto" loading="lazy"></a><figcaption style="font:12px sans-serif;color:#5b6470">Source: <a href="https://www.quantisnow.com/data/insider-buying">Quantisnow Insider Buying Index</a> by Quantisnow</figcaption></figure>