Mark Massey's AltaRock Partners holds 876K shares of Transdigm Group Incorporated (TDG) worth about $1.2B as of June 30, 2026, according to the 13F-HR filed with the SEC on August 17, 2026. The position is 27.51% of the reported portfolio, the 2nd largest of 8 stock positions. Mark Massey trimmed the share count by 4% in 2026 Q2.
What did the 2026 Q2 filing report for TDG?
As of June 30, 2026, from the 13F-HR filed August 17, 2026.
| Value | |
|---|---|
| Portfolio weight | 27.51% |
| Shares | 876K |
| Reported value | $1.2B |
| Rank in portfolio | 2nd of 8 |
| Largest holding | AMZN at 32.21% |
| Top three holdings | 80.26% of the book |
| Change this quarter | -4% shares |
How concentrated is Mark Massey in TDG?
TDG at 27.51% is 2.2 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 TDG was 25.54% of the book.
Where does TDG sit in the Mark Massey portfolio?
TDG ranks 2nd of 8 stock positions in the Mark Massey portfolio at 27.51%, above the fund's average stock position of 12%. The TDG cut was the 6th 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 TDG?
Mark Massey first reported TDG in the quarter ended December 31, 2014. The weight peaked at 32.29% in 2015 Q4. Last quarter the fund cut the position by 6%. Every reported trade is on the Mark Massey TDG trade history page.
Did other funds buy or sell TDG in 2026 Q2?
Among the other tracked funds that had filed for 2026 Q2 as of August 17, 2026, 5 hold TDG. The largest buyer of TDG this quarter was Daniel Loeb. The largest sellers were Vulcan Value Partners and Stephen Mandel. Every tracked holder of TDG is on the TDG ownership page.
FAQ
What share of the Mark Massey portfolio is TDG?
TDG is 27.51% of the Mark Massey portfolio as of 2026 Q2, the 2nd largest of 8 stock positions.
What is the TDG stake of Mark Massey worth?
Mark Massey holds 876K shares of TDG, worth about $1.2B at June 30, 2026 prices, 27.51% 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 TDG position in 2026 Q2?
Mark Massey trimmed the share count by 4% in 2026 Q2.