According to recent filings covering the 90 days ending February 07, 2026, the three most significant insider holders at Arcellx are TenPercentOwner Partners 15, L.P. Nea (4.75Mn shares), TenPercentOwner Enterprise Associates 15, L.P. New (4.75Mn shares), TenPercentOwner Holdings A/S Novo (4.02Mn shares).
| Holder | Position | Shares | Report Date |
|---|---|---|---|
| Partners 15, L.P. Nea | 4,745,262 | 22 Dec, 2022 | |
| Enterprise Associates 15, L.P. New | 4,745,262 | 22 Dec, 2022 | |
| Holdings A/S Novo | 4,016,878 | 09 Feb, 2022 | |
| Lewis T Williams | 2,095,114 | 09 Feb, 2022 | |
| One Capital Management, Llc Sr | 1,658,780 | 15 May, 2023 | |
| Jill Carroll | 1,479,148 | 25 Mar, 2024 | |
| Rami Elghandour | See Remarks | 782,467 | 06 Jan, 2026 |
| Michelle Gilson | Chief Financial Officer | 64,832 | 06 Jan, 2026 |
| Christopher Heery | Chief Medical Officer | 23,749 | 14 Jan, 2026 |
| David Charles Lubner | 21,659 | 20 Jan, 2026 | |
| Ali Behbahani | 4,631 | 14 Aug, 2025 | |
| Mohamad Makhzoumi | 283 | 22 Dec, 2022 | |
| Peter W. Sonsini | 12 | 22 Dec, 2022 |
* Please note that the shares above only reflect shares from the fund portfolio and the institutional portfolio. Shares from the personal portfolio are excluded from this Institutional Ownership Page. See these insiders' latest transactions here on Insider Page.
| Transaction Date | Insider Name | Security Class | Transaction Type | Shares Traded | Price | Shares Remaining | Ownership | Code |
|---|---|---|---|---|---|---|---|---|
| 20 Jan, 2026 | David Charles Lubner | Common Stock | D | 6,000 | $75.00 | 21,659 | D | S |
| 20 Jan, 2026 | David Charles Lubner | Common Stock | A | 6,000 | $6.28 | 27,659 | D | M |
| 14 Jan, 2026 | Christopher Heery | Common Stock | D | 5,882 | $68.51 | 23,749 | D | S |
| 13 Jan, 2026 | Christopher Heery | Common Stock | D | 7,437 | $65.51 | 29,631 | D | S |
| 12 Jan, 2026 | Christopher Heery | Common Stock | D | 6,131 | $64.15 | 37,068 | D | S |
| 06 Jan, 2026 | Rami Elghandour | Common Stock | A | 55,991 | $0.00 | 782,467 | D | M |
| 06 Jan, 2026 | Christopher Heery | Common Stock | A | 13,064 | $0.00 | 43,199 | D | M |
| 06 Jan, 2026 | Christopher Heery | Common Stock | A | 13,064 | $0.00 | 43,199 | D | M |
| 06 Jan, 2026 | Michelle Gilson | Common Stock | A | 20,530 | $0.00 | 64,832 | D | M |
| 03 Jan, 2026 | Rami Elghandour | Common Stock | A | 53,098 | $0.00 | 726,476 | D | M |
| 03 Jan, 2026 | Christopher Heery | Common Stock | A | 16,520 | $0.00 | 30,135 | D | M |
| 03 Jan, 2026 | Christopher Heery | Common Stock | A | 16,520 | $0.00 | 30,135 | D | M |
| 03 Jan, 2026 | Michelle Gilson | Common Stock | A | 15,340 | $0.00 | 44,302 | D | M |
| 02 Jan, 2026 | Rami Elghandour | Common Stock | A | 55,459 | $0.00 | 673,378 | D | M |
| 02 Jan, 2026 | Christopher Heery | Common Stock | A | 13,021 | $0.00 | 13,615 | D | M |
| 02 Jan, 2026 | Christopher Heery | Common Stock | A | 13,021 | $0.00 | 13,615 | D | M |
| 02 Jan, 2026 | Michelle Gilson | Common Stock | A | 20,496 | $0.00 | 28,962 | D | M |
| 17 Nov, 2025 | Christopher Heery | Common Stock | D | 340 | $90.00 | 284 | D | S |
| 15 Oct, 2025 | Michelle Gilson | Common Stock | D | 5,364 | $91.04 | 8,466 | D | S |
| 06 Oct, 2025 | Michelle Gilson | Common Stock | D | 1,064 | $86.22 | 13,830 | D | S |