Mark Massey's AltaRock Partners holds 2.33M shares of Microsoft Corp (MSFT) worth about $870.8M as of June 30, 2026, according to the 13F-HR filed with the SEC on August 17, 2026. The position is 20.54% of the reported portfolio, the 3rd largest of 8 stock positions. Mark Massey added 25% to the share count in 2026 Q2.
What did the 2026 Q2 filing report for MSFT?
As of June 30, 2026, from the 13F-HR filed August 17, 2026.
| Value | |
|---|---|
| Portfolio weight | 20.54% |
| Shares | 2.33M |
| Reported value | $870.8M |
| Rank in portfolio | 3rd of 8 |
| Largest holding | AMZN at 32.21% |
| Top three holdings | 80.26% of the book |
| Change this quarter | +25% shares |
How concentrated is Mark Massey in MSFT?
MSFT at 20.54% is 1.6 times the average stock position in the Mark Massey portfolio, which is 12%. The largest holding is AMZN at 32.21%. The three largest stocks together are 80.26% of the reported book. A quarter earlier MSFT was 16.75% of the book.
Where does MSFT sit in the Mark Massey portfolio?
MSFT ranks 3rd of 8 stock positions in the Mark Massey portfolio at 20.54%, above the fund's average stock position of 12%. The MSFT addition was the 3rd largest of the quarter's 8 position changes by percent change to portfolio. Across the 2026 Q2 portfolio, Mark Massey reported 8 stock positions, with no position opened or closed. The total portfolio value is about $4.2B, up 3% from the prior quarter.
How long has Mark Massey held MSFT?
Mark Massey first reported MSFT in the quarter ended June 30, 2021. The weight peaked at 24.33% in 2025 Q3. Last quarter the fund cut the position by 10%. Every reported trade is on the Mark Massey MSFT trade history page.
Did other funds buy or sell MSFT in 2026 Q2?
Among the other tracked funds that had filed for 2026 Q2 as of August 17, 2026, 36 hold MSFT. Of those, 3 opened it this quarter. Another 4 sold out of it. The largest buyers of MSFT this quarter were Lewis Sanders, Dodge & Cox Stock Fund and Bill Ackman. The largest sellers were Eagle Capital Management, Polen Capital Management and Chris Hohn. Every tracked holder of MSFT is on the MSFT ownership page.
FAQ
What share of the Mark Massey portfolio is MSFT?
MSFT is 20.54% of the Mark Massey portfolio as of 2026 Q2, the 3rd largest of 8 stock positions.
What is the MSFT stake of Mark Massey worth?
Mark Massey holds 2.33M shares of MSFT, worth about $870.8M at June 30, 2026 prices, 20.54% of the reported portfolio.
What are the largest holdings of Mark Massey?
The largest stock positions of Mark Massey as of 2026 Q2 are AMZN (32.21%), TDG (27.51%) and MSFT (20.54%), together 80.26% of the book.
Did Mark Massey's AltaRock Partners change its MSFT position in 2026 Q2?
Mark Massey added 25% to the share count in 2026 Q2.