LANSDOWNE PARTNERS (UK) LLP — ARM HOLDINGS PLC ARM: Quarterly 13F Position History
LANSDOWNE PARTNERS (UK) LLP has reported ARM HOLDINGS PLC (ARM) on 3 13F-HR filings in Pactolio's tracked window, first appearing in Q3 2025. As of Q1 2026, the position is sized at 935,503 shares ($141.5M market value, 7.58% of the equity book). Quarter-over-quarter share count change: + 463,427 (+98.2%) .
- 935,503Shares Held (Latest Filing)
- $141.5MReported Market Value (Latest Filing)
- 7.58%Portfolio Weight (% of 13F Equity Book)
- +463,427Quarter-over-Quarter Share Change
- +$89.9MQuarter-over-Quarter Value Change
- 935,503Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 3 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q1 2026 | 935,503 | +463,427 | +98.2% | $141.5M | 7.58% | $151.28 |
| Q4 2025 | 472,076 | +412,101 | +687.1% | $51.6M | 3.78% | $109.31 |
| Q3 2025 | 59,975 | — | — | $8.5M | 0.70% | $141.49 |
Methodology & FAQ
How This Position History Is Sourced
Each row is one SEC Form 13F-HR filing disclosing this position. Share count, market value, and reported quarter are taken verbatim from the filing; portfolio weight is recomputed against the same filing's total reported equity book. Implied price-per-share is market value divided by shares — a quarter-end mark, not the manager's cost basis. See the full methodology document for the normalization rules.
When did LANSDOWNE PARTNERS (UK) LLP first disclose a ARM position in 13F-HR filings?
LANSDOWNE PARTNERS (UK) LLP first reported ARM HOLDINGS PLC (ARM) on its 13F-HR filing for the period ending 2025-09-30 (Q3 2025). The position has appeared on 3 reported quarters within Pactolio's tracked window.
What was LANSDOWNE PARTNERS (UK) LLP's most recent quarter-over-quarter share-count change in ARM?
Between Q4 2025 and Q1 2026, LANSDOWNE PARTNERS (UK) LLP added 463,427 shares of ARM (+98.2%), bringing the total reported position to 935,503 shares at a market value of $141.5M.
Does the implied price-per-share represent LANSDOWNE PARTNERS (UK) LLP's cost basis in ARM?
No. The implied price-per-share column is the 13F-HR reported market value divided by reported share count on the filing date (end of quarter). It is a quarter-end mark, not a cost basis or transaction price. Use it as a sanity check on the value column, not as an indicator of the manager's entry or exit price.