Breaking down the stocks Mark Massey and Scott Bradford (AltaRock Partners) bought, sold, and held in Q2 2026, including their holdings at the end of the quarter. All data sourced from AltaRock Partners' 13F filed on August 17, 2026.
Who are Mark Massey, Scott Bradford and AltaRock Partners?
AltaRock Partners is a highly concentrated investment firm founded by Mark Massey and Scott Bradford, both Harvard MBA graduates with distinguished investment backgrounds. Massey previously worked at Seth Klarman's Baupost Group, while Bradford gained experience at Fiduciary Management Associates. The firm maintains an extremely focused portfolio typically comprising fewer than ten holdings with a combined value of approximately $4.8 billion. AltaRock's investment philosophy centers on identifying exceptional businesses with durable competitive advantages and holding them for the long term.
Altarockpartners.com
Q2 '26 13F filed with SEC
Holdings in Q2 2026
| Ticker | Company | Weight | Change | Value |
|---|---|---|---|---|
| Amazon | 32.2% | Trimmed (-24%) | $1.37B | |
| TransDigm | 27.5% | Trimmed (-4%) | $1.17B | |
| Microsoft | 20.5% | Added (+25%) | $870.81M | |
| Mastercard Inc-Class A | 9.3% | Added (+46%) | $392.65M | |
| Visa Inc-Class A Shrs | 6.8% | Added (+68%) | $286.98M | |
| Moodys | 3.2% | Trimmed (-65%) | $137.06M | |
| Alphabet | 0.4% | Trimmed (-3%) | $15.01M | |
| Hilton | 0.1% | Trimmed (-1%) | $5.02M |
Current Investment Strategy
AltaRock Partners, the Beverly, Massachusetts-based firm run by Baupost alum Mark Massey and Scott Bradford, maintained its ultra-concentrated, buy-and-hold value approach through Q2 2026, deploying roughly $4.8 billion across just eight wide-moat compounders—Amazon, TransDigm, Microsoft, Mastercard, Visa, Moody's, Alphabet, and Hilton—without initiating a single new position or exiting an existing one. The firm's Buffett-Munger-inspired philosophy remains anchored in identifying durable competitive moats across technology, payments, credit analytics, aerospace, and hospitality, favoring patient, low-turnover ownership stakes in cash-generative franchises over short-term trading activity.
New Investments
AltaRock Partners did not open any new positions during Q2 2026.
Added, Trimmed, and Exited
Added
AltaRock Partners added meaningfully to three of its financial and technology holdings this quarter. The firm increased its Microsoft stake by roughly 25% (from 1,867,537 to 2,334,482 shares), pushed its Visa Inc-Class A Shrs position up nearly 68% (from 498,677 to 836,470 shares), and grew its Mastercard Inc-Class A holding by about 46% (from 522,836 to 764,507 shares). These additions combined with price appreciation drove the value of these three positions up substantially, with Visa Inc-Class A Shrs alone posting a 90%+ quarter-over-quarter return.
What it means: The aggressive build-out of the payments duopoly (Visa Inc-Class A Shrs and Mastercard Inc-Class A) alongside a continued vote of confidence in Microsoft suggests AltaRock Partners is doubling down on businesses with entrenched competitive moats and recurring, high-margin revenue streams — consistent with the firm's stated philosophy of concentrating capital in durable, well-understood compounders rather than chasing new ideas.
Trimmed
The most notable reduction was in Moodys, where AltaRock Partners cut its position by nearly 65% (from 862,036 to 302,624 shares), resulting in a steep 63.6% decline in position value. The firm also meaningfully reduced its Amazon stake by about 24% (from 7,567,946 to 5,729,972 shares), leading to a 13.4% drop in value. Smaller trims were made to TransDigm, Alphabet, and Hilton, each reduced by low single-digit percentages in share count, though price appreciation actually pushed the value of these three positions higher despite the share reductions.
What it means: The dramatic cut to Moodys stands out as a potential conviction shift, possibly reflecting valuation concerns or a reassessment of the ratings agency's growth trajectory, while the Amazon trim may simply reflect prudent profit-taking after a strong run. The marginal trims to TransDigm, Alphabet, and Hilton appear more like routine rebalancing rather than a change in thesis, since the firm let winners run even as it lightly pared back share counts.
Exited
There were no fully liquidated positions this quarter — AltaRock Partners maintained its entire roster of holdings.
What it means: With zero full exits and no new positions initiated, this quarter reflects a "stay the course" approach for most of the portfolio, reinforcing the firm's reputation for extreme concentration and low turnover, with the notable exception being the sharp de-risking of the Moodys stake.
Disclaimer: All posts are for informational purposes only. They are NOT a recommendation to buy or sell the securities discussed. Please do your own research and due diligence before investing your money.
