LANSDOWNE PARTNERS (UK) LLP: ARM HOLDINGS PLC (ARM): Quarterly 13F Position History
As of Q2 2026, LANSDOWNE PARTNERS (UK) LLP reported 1,072,493 shares of ARM HOLDINGS PLC (ARM), worth $380.3M and representing 15.6% of its 13F equity book. Quarter-over-quarter share count change: + 136,990 (+14.6%) . The position first appeared in Q3 2025 and has been disclosed across 4 13F-HR filings in Pactolio's tracked window.
- 1,072,493Shares Held (Latest Filing)
- $380.3MReported Market Value (Latest Filing)
- 15.6%Portfolio Weight (% of 13F Equity Book)
- +136,990Quarter-over-Quarter Share Change
- +$238.8MQuarter-over-Quarter Value Change
- 1,072,493Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 4 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q2 2026 | 1,072,493 | +136,990 | +14.6% | $380.3M | 15.6% | $354.6 |
| Q1 2026 | 935,503 | +463,427 | +98.2% | $141.5M | 7.6% | $151.3 |
| Q4 2025 | 472,076 | +412,101 | +687.1% | $51.6M | 3.8% | $109.3 |
| Q3 2025 | 59,975 | – | – | $8.5M | 0.7% | $141.5 |
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 rather than 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 4 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 Q1 2026 and Q2 2026, LANSDOWNE PARTNERS (UK) LLP added 136,990 shares of ARM (+14.6%), bringing the total reported position to 1,072,493 shares at a market value of $380.3M.
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.