SEC Form 4
Inhibrx Biosciences, Inc. (INBX) insider trading
In the 12 months to Oct 26, 2026, one INBX insider reported open-market sales of $279.0K across 2 filings; 3 insiders bought $6.3M.
Latest filing · Last 12 months · Source: SEC EDGAR · How we count
- Open-market sales
- $279.0K
- 2 filings · 1 insider
- Open-market purchases
- $6.3M
- 7 filings
Who traded INBX, and when
- Purchase
- Sale
INBX daily close from Oct 27, 2025 to Oct 26, 2026, between $58.39 and $141.84, last $87.88. 2 sale and 7 purchase filings by 4 insiders, marked at their filing dates. Mark Lappe, Chief Executive Officer: bought $4.5M across 3 filings, first filed Sep 8, 2026, last Oct 14, 2026. Jon Faiz Kayyem, Director: bought $1.6M across 3 filings, first filed Sep 8, 2026, last Sep 23, 2026. Douglas Forsyth, Director: bought $286.6K across 1 filing, first filed Sep 8, 2026, last Sep 8, 2026. Kimberly Manhard, Director: sold $279.0K across 2 filings, first filed Sep 10, 2026, last Sep 15, 2026.
Largest mark · tap a row for others
Mark Lappe · Chief Executive Officer
Purchase $2,645,399
25,000 shares at $105.82 avg
Filed Sep 8, 2026
Close on filing date $114.34
Mark Lappe · Chief Executive Officer
Chief Executive Officer
$4.5M boughtJon Faiz Kayyem · Director
Director
$1.6M boughtDouglas Forsyth · Director
Director
$286.6K boughtKimberly Manhard · Director
Director
$279.0K soldOpen-market trades
9 filings in the last 12 months| Insider | Role | Sold | Bought | Filings | Pre-arranged (10b5-1) | Last filed |
|---|---|---|---|---|---|---|
| Mark Lappe | Chief Executive Officer | — | $4.5M | 3 | — | |
| Jon Faiz Kayyem | Director | — | $1.6M | 3 | — | |
| Douglas Forsyth | Director | — | $286.6K | 1 | — | |
| Kimberly Manhard | Director | $279.0K | — | 2 | — |
| Filed | Insider | Type | Shares | Avg price | Value | Held after | Source |
|---|---|---|---|---|---|---|---|
traded | Mark Lappe Chief Executive Officer | Purchase | 10,040 | $84.56 | $849.0K | Multiple accounts | |
traded | Mark Lappe Chief Executive Officer | Purchase | 10,000 | $99.88 | $998.8K | 740,548 | |
traded | Jon Faiz Kayyem Director | Purchase | 5,000 | $100.00 | $500.0K | 434,360 | |
traded | Jon Faiz Kayyem Director | Purchase | 5,000 | $100.00 | $500.0K | 429,360 | |
traded | Kimberly Manhard Director | Sale | 1,500 | $109.03 | $163.5K | 7,500 | |
traded | Kimberly Manhard Director | Sale | 1,000 | $115.47 | $115.5K | 9,000 | |
traded | Douglas Forsyth Director | Purchase | 2,500 | $114.65 | $286.6K | 227,064 | |
traded | Mark Lappe Chief Executive Officer | Purchase | 25,000 | $105.82 | $2.6M | 719,648 | |
traded | Jon Faiz Kayyem Director | Purchase | 5,000 | $113.52 | $567.6K | 424,360 |
GET /stocks/filings/vX/form-4?tickers=INBX&filing_date.gte=2025-10-26&sort=filing_date.desc&limit=500{
"status": "OK",
"results": [
{
"tickers": [
"INBX"
],
"issuer_cik": "0002007919",
"owner_cik": "0001366074",
"accession_number": "0001366074-26-000006",
"form_type": "4",
"filing_date": "2026-10-14",
"period_of_report": "2026-10-14",
"issuer_name": "Inhibrx Biosciences, Inc.",
"issuer_trading_symbol": "INBX",
"owner_name": "Lappe Mark",
"is_director": true,
"is_officer": true,
"is_ten_percent_owner": false,
"is_other": false,
"officer_title": "Chief Executive Officer",
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Common Stock",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-10-14",
"transaction_code": "P",
"equity_swap_involved": false,
"transaction_shares": 2449,
"transaction_price_per_share": 84.0707,
"transaction_acquired_disposed": "A",
"shares_owned_following_transaction": 167449,
"transaction_value": 205889.1443,
"not_subject_to_section_16": false,
"direct_or_indirect": "I",
"nature_of_ownership": "By Lappe Descendants' Trust",
"footnotes": [
{
"id": "F1",
"description": "The shares were purchased in multiple transactions at prices ranging from $83.61 to $84.59 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected."
},
{
"id": "F4",
"description": "These securities are directly owned by a trust, for the benefit of the reporting person's immediate family. Mark P. Lappe, as an immediate family member of the beneficiaries of the trust, may be deemed to indirectly beneficially own the securities owned by the trust."
}
]
},
{
"tickers": [
"INBX"
],
"issuer_cik": "0002007919",
"owner_cik": "0001366074",
"accession_number": "0001366074-26-000006",
"form_type": "4",
"filing_date": "2026-10-14",
"period_of_report": "2026-10-14",
"issuer_name": "Inhibrx Biosciences, Inc.",
"issuer_trading_symbol": "INBX",
"owner_name": "Lappe Mark",
"is_director": true,
"is_officer": true,
"is_ten_percent_owner": false,
"is_other": false,
"officer_title": "Chief Executive Officer",
"security_type": "non_derivative",
"record_type": "transaction",
"security_title": "Common Stock",
"transaction_timeliness": "O",
"aff_10b5_one": false,
"transaction_date": "2026-10-14",
"transaction_code": "P",
"equity_swap_involved": false,
"transaction_shares": 2470,
"transaction_price_per_share": 84.9992,
"transaction_acquired_disposed": "A",
"shares_owned_following_transaction": 745488,
"transaction_value": 209948.024,
"not_subject_to_section_16": false,
"direct_or_indirect": "I",
"nature_of_ownership": "By the Lappe Family Trust",
"footnotes": [
{
"id": "F3",
"description": "The shares were purchased in multiple transactions at prices ranging from $84.65 to $85.62 inclusive. The reported price reflects the weighted-average purchase price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transactions were effected."
},
{
"id": "F2",
"description": "These securities are directly owned by the Lappe Family Trust. Mark P. Lappe is a trustee of the Lappe Family Trust and, in such capacity, may be deemed to indirectly beneficially own the securities owned by the Lappe Family Trust."
}
]
}
]
}
// trimmed to 2 resultsThe response includes every Form 4 record; this page keeps open-market purchases and sales on common stock and removes duplicate joint-filer rows.
How to read this page
- Open-market purchase or sale
- A buy or sell of the company's stock at market price. Grants, option exercises, shares withheld for tax, gifts and employee stock plan purchases are listed separately and not counted.
- Filing date
- Insiders have two business days to report a trade. Totals and the chart use the filing date, when the trade became public.
Frequently asked questions
Has Inhibrx Biosciences, Inc.'s CEO sold stock?
No. Mark Lappe (CEO) made no open-market sales filed as CEO in the last 12 months.
How current is INBX’s insider data?
These are INBX Form 4 filings from the last year, refreshed daily. The Massive Form 4 API has the full, continuously updated record.
What counts as an open-market buy or sell?
Only purchases and sales at the market price. Option exercises, grants, gifts, and shares withheld for taxes are reported on Form 4 but are left out of the buy and sell totals.
Build with AI
Track INBX insider trades with your agent
This page joins two Massive endpoints: Form 4 filings and daily prices. Ask an agent to watch for new filings:
Using the Massive API (massive.com/docs/llms.txt), check Form 4 filings for INBX every day with transaction_code=P and tell me when an insider files an open-market purchase, with their role, shares, price and the filing link.
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