Second Mountain Financial

Michael Sonnenfeldt, the founder and chairman, leads investment decisions. He draws on a network of Tiger 21 members — many of whom are former founders and operators with domain expertise — to evaluate opportunities. The firm does not publish the names of additional investment committee members.

Second Mountain's deal flow originates primarily through the 1,000-plus members of Tiger 21, the peer network Sonnenfeldt founded in 1999. Members often bring businesses they own or deals they have accessed to the platform. This gives the firm a sourcing channel that is difficult for outside managers to replicate.

No. While Sonnenfeldt's personal capital is involved, Second Mountain is structured as a co-investment platform that allows Tiger 21 members and select outside investors to participate deal-by-deal. It is legally separate from Tiger 21's membership operations and does not function as a single-family office.

Michael Sonnenfeldt founded both entities. Tiger 21 is a peer-membership organization for ultra-high-net-worth investors; Second Mountain is a separate investment platform that offers Tiger 21 members access to private-market deals. The two share a common founder and overlapping network but maintain distinct legal and operational structures.

The firm focuses on commercial real estate, energy transition infrastructure, private credit, and secondary-market special situations. Sonnenfeldt has publicly identified climate and sustainability as a key investment theme, channeling capital into renewable energy project finance alongside traditional real estate acquisitions.