One name, Microsoft Corp (MSFT), is 32.15% of what Mark Massey's AltaRock Partners reports for 2026 Q3, according to the 13F-HR filed with the SEC on November 13, 2026. The stake is 2.64M shares worth about $1.35B, the largest of 8 stock positions. Mark Massey added 13% to the share count in 2026 Q3.
What did the 2026 Q3 filing report for MSFT?
As of September 30, 2026, from the 13F-HR filed November 13, 2026.
| Value | |
|---|---|
| Portfolio weight | 32.15% |
| Shares | 2.64M |
| Reported value | $1.35B |
| Rank in portfolio | 1st of 8 |
| Next largest holding | AMZN at 28.53% |
| Top three holdings | 82.35% of the book |
| Change this quarter | +13% shares |
How concentrated is Mark Massey in MSFT?
MSFT at 32.15% is 2.6 times the average stock position in the Mark Massey portfolio, which is 13%. The next largest holding is AMZN at 28.53%. The three largest stocks together are 82.35% of the reported book. A quarter earlier MSFT was 20.54% of the book.
Where does MSFT sit in the Mark Massey portfolio?
MSFT is the largest of 8 stock positions in the Mark Massey portfolio at 32.15%, above the fund's average stock position of 13%. The MSFT addition was the 2nd largest of the quarter's 7 position changes by percent change to portfolio. Across the 2026 Q3 portfolio, Mark Massey reported 8 stock positions, with no position opened or closed. The total portfolio value is about $4.21B, down 1% from the prior quarter.
How long has Mark Massey held MSFT?
Mark Massey first reported MSFT in the quarter ended June 30, 2021. The current weight is the highest the fund has reported for the name. Last quarter the fund added to the position by 25%. Every reported trade is on the Mark Massey MSFT trade history page.
Did other funds buy or sell MSFT in 2026 Q3?
Among the other tracked funds that had filed for 2026 Q3 as of November 13, 2026, 17 hold MSFT. One other tracked fund sold out of it. The largest buyers of MSFT this quarter were Donald Yacktman, Parnassus Endeavor Fund and Richard Pzena. The largest sellers were Lewis Sanders, Polen Capital Management and Nathaniel Simons. Every tracked holder of MSFT is on the MSFT ownership page.
FAQ
What share of the Mark Massey portfolio is MSFT?
MSFT is 32.15% of the Mark Massey portfolio as of 2026 Q3, the largest of 8 stock positions.
What is the MSFT stake of Mark Massey worth?
Mark Massey holds 2.64M shares of MSFT, worth about $1.35B at September 30, 2026 prices, 32.15% of the reported portfolio.
What are the largest holdings of Mark Massey?
The largest stock positions of Mark Massey as of 2026 Q3 are MSFT (32.15%), AMZN (28.53%) and TDG (21.67%), together 82.35% of the book.
Did Mark Massey's AltaRock Partners change its MSFT position in 2026 Q3?
Mark Massey added 13% to the share count in 2026 Q3.