SEC EDGAR Form 13F
AltaRock Partners
AltaRock Partners is a concentrated quality and value-oriented investment manager associated with Mark Massey.
Latest Form 13F: 8 long U.S. equity positions, $4.2B reported value for the period ended Jun 30, 2026, led by AMAZON.COM INC, TRANSDIGM GROUP INC, and MICROSOFT CORP.
CIK: 1631014 · Filed: Aug 17, 2026 · Period: Jun 30, 2026
Reported value
$4.2B
Positions
8
Key person
Mark Massey
Style
Concentrated quality/value
Top holding
AMZN · AMAZON.COM INC
Period
Jun 30, 2026
Filed
Aug 17, 2026
CIK
1631014
What a 13F does not show
Form 13F covers many reportable long U.S. equity positions at quarter end. It does not show every asset type, short positions, hedges, intraperiod trades, or current holdings after the report date. Use it as ownership context, not investment advice.
Read the 13F guide →AMZN
AMAZON.COM INC
Portfolio weight
32.21%
TDG
TRANSDIGM GROUP INC
Portfolio weight
27.51%
MSFT
MICROSOFT CORP
Portfolio weight
20.54%
MA
MASTERCARD INC-CLASS A
Portfolio weight
9.26%
V
VISA INC-CLASS A SHRS
Portfolio weight
6.77%
Top reported holdings
Showing the top 8 positions by reported value. Source: SEC EDGAR Form 13F; period 2026-06-30; filed 2026-08-17.
| # | Ticker | Company | Shares | Value | Portfolio % | QoQ change |
|---|---|---|---|---|---|---|
| 1 | AMZN | AMAZON.COM INC | 5.7M | $1.4B | 32.21% | -24.3% |
| 2 | TDG | TRANSDIGM GROUP INC | 875.8K | $1.2B | 27.51% | -3.7% |
| 3 | MSFT | MICROSOFT CORP | 2.3M | $871M | 20.54% | +25.0% |
| 4 | MA | MASTERCARD INC-CLASS A | 764.5K | $393M | 9.26% | +46.2% |
| 5 | V | VISA INC-CLASS A SHRS | 836.5K | $287M | 6.77% | +67.7% |
| 6 | MCO | MOODYS CORP | 302.6K | $137M | 3.23% | -64.9% |
| 7 | GOOGL | ALPHABET INC-CL A | 42.0K | $15M | 0.35% | -3.2% |
| 8 | HLT | HILTON WORLDWIDE | 15.2K | $5M | 0.12% | -0.9% |
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