Altimeter Capital Management, LP: ARM HOLDINGS PLC (ARM): Quarterly 13F Position History
As of Q2 2026, Altimeter Capital Management, LP reported 1,641,972 shares of ARM HOLDINGS PLC (ARM), worth $582.2M and representing 5.9% of its 13F equity book. Quarter-over-quarter share count change: 73,468 (-4.3%) . The position first appeared in Q1 2025 and has been disclosed across 6 13F-HR filings in Pactolio's tracked window.
- 1,641,972Shares Held (Latest Filing)
- $582.2MReported Market Value (Latest Filing)
- 5.9%Portfolio Weight (% of 13F Equity Book)
- 73,468Quarter-over-Quarter Share Change
- +$322.7MQuarter-over-Quarter Value Change
- 1,715,440Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 6 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q2 2026 | 1,641,972 | 73,468 | -4.3% | $582.2M | 5.9% | $354.6 |
| Q1 2026 | 1,715,440 | +1,715,440 | – | $259.5M | 4.6% | $151.3 |
| Q4 2025 | 0 | 1,098,139 | -100.0% | $0 | 0.0% | – |
| Q3 2025 | 1,098,139 | +164,931 | +17.7% | $155.4M | 2.0% | $141.5 |
| Q2 2025 | 933,208 | +757,608 | +431.4% | $150.9M | 2.2% | $161.7 |
| Q1 2025 | 175,600 | – | – | $18.8M | 0.4% | $106.8 |
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 Altimeter Capital Management, LP first disclose a ARM position in 13F-HR filings?
Altimeter Capital Management, LP first reported ARM HOLDINGS PLC (ARM) on its 13F-HR filing for the period ending 2025-03-31 (Q1 2025). The position has appeared on 6 reported quarters within Pactolio's tracked window.
What was Altimeter Capital Management, LP's most recent quarter-over-quarter share-count change in ARM?
Between Q1 2026 and Q2 2026, Altimeter Capital Management, LP reduced its ARM position by 73,468 shares (-4.3%), leaving 1,641,972 shares at a market value of $582.2M.
Does the implied price-per-share represent Altimeter Capital Management, LP'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.