One name, Amazon.com Inc (AMZN), is 32.21% of what Mark Massey's AltaRock Partners reports for 2026 Q2, according to the 13F-HR filed with the SEC on August 17, 2026. The stake is 5.73M shares worth about $1.4B, the largest of 8 stock positions. Mark Massey trimmed the share count by 24% in 2026 Q2.
What did the 2026 Q2 filing report for AMZN?
As of June 30, 2026, from the 13F-HR filed August 17, 2026.
| Value | |
|---|---|
| Portfolio weight | 32.21% |
| Shares | 5.73M |
| Reported value | $1.4B |
| Rank in portfolio | 1st of 8 |
| Next largest holding | TDG at 27.51% |
| Top three holdings | 80.26% of the book |
| Change this quarter | -24% shares |
How concentrated is Mark Massey in AMZN?
AMZN at 32.21% is 2.6 times the average stock position in the Mark Massey portfolio, which is 12%. The next largest holding is TDG at 27.51%. The three largest stocks together are 80.26% of the reported book. A quarter earlier AMZN was 38.2% of the book.
Where does AMZN sit in the Mark Massey portfolio?
AMZN is the largest of 8 stock positions in the Mark Massey portfolio at 32.21%, above the fund's average stock position of 12%. The AMZN cut was the 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 AMZN?
Mark Massey first reported AMZN in the quarter ended March 31, 2022. The weight peaked at 38.2% in 2026 Q1. Last quarter the fund added to the position by 3%. Every reported trade is on the Mark Massey AMZN trade history page.
Did other funds buy or sell AMZN in 2026 Q2?
Among the other tracked funds that had filed for 2026 Q2 as of August 17, 2026, 29 hold AMZN. One other tracked fund sold out of it. The largest buyers of AMZN this quarter were Dodge & Cox Stock Fund, David Tepper and Seth Klarman. The largest sellers were Lewis Sanders, Eagle Capital Management and Bill Ackman. Every tracked holder of AMZN is on the AMZN ownership page.
FAQ
What share of the Mark Massey portfolio is AMZN?
AMZN is 32.21% of the Mark Massey portfolio as of 2026 Q2, the largest of 8 stock positions.
What is the AMZN stake of Mark Massey worth?
Mark Massey holds 5.73M shares of AMZN, worth about $1.4B at June 30, 2026 prices, 32.21% 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 AMZN position in 2026 Q2?
Mark Massey trimmed the share count by 24% in 2026 Q2.