Mark Massey

Biography

Mark Massey holds an MBA from Harvard and worked at the Baupost Group before founding AltaRock Partners in 2002. The firm runs a concentrated portfolio and says it invests like a long-term owner, looking for superior businesses with durable competitive advantages bought at reasonable prices, without using leverage.

In their own words

AltaRock Partners’s largest US holdings

From the Q2 2026 13F, worth $4.2bn in total. See every holding and change

1. Amazon.comAMZN32.2%
2. Transdigm GroupTDG27.5%
3. MicrosoftMSFT20.5%
4. MastercardMA9.3%
5. VisaV6.8%
6. Moody'sMCO3.2%
7. AlphabetGOOG0.3%
8. Hilton WorldwideHLT0.1%