Altas Partners

Andrew Sheiner, the firm's founder and managing partner, leads the investment committee alongside managing partners Paul Nicoletti and Chris McElhone. Sheiner previously served as a senior managing director at Onex, where he co-headed the buyout group. The firm maintains a flat partnership structure with no external investment committee, giving the three managing partners full discretion on capital deployment (per media reports, 2023).

Altas operates a concentrated portfolio model, targeting 4 to 6 active control investments at any one time, rather than the 12–15 positions typical of mid-market buyout funds. The firm draws on long-dated institutional capital from pension funds and sovereign wealth investors that does not face the same redemption pressure as a traditional 10-year fund structure. This allows Altas to hold assets for extended periods and underwrite to a 10-to-15-year ownership horizon.

There is no formal corporate relationship between Altas and Onex. Andrew Sheiner, Altas's founder, worked at Onex from 1999 to 2012, rising to senior managing director and co-head of Onex Partners, the firm's flagship buyout platform. Several senior Altas professionals, including partners Chris McElhone and Paul Nicoletti, also previously held roles at Onex before joining Sheiner to launch the independent firm.

Altas exclusively pursues majority and significant-minority control investments in North American mid-market companies. The firm does not operate a fund-of-funds program, invest in third-party managed vehicles, or participate as a limited partner in other private equity funds. All capital is deployed through its flagship buyout fund series into direct company ownership positions.

The firm explicitly avoids minority growth equity, venture capital, distressed debt, and real asset strategies. Altas has publicly stated it will not invest in sectors it considers cyclical or capital-intensive, including energy, materials, and heavy industrials. The firm also avoids auction processes where it cannot secure a proprietary or negotiated position (per media reports, 2023).

Altas relies on a concentrated origination model built through operating-partner relationships and long-standing intermediary networks in North American healthcare, software, and business services. The partnership team personally leads proprietary outreach to founder-owned and family-held businesses rather than depending on broad auction participation. The firm's holding-company flexibility often positions it as a preferred buyer for sellers seeking a permanent home rather than a three-to-five-year flip.

Altas has limited appetite for co-investing alongside other general partners unless it retains a control or shared-control governance position. The firm occasionally syndicates large equity positions to institutional co-investors from its own LP base during acquisition, but it does not act as a minority co-investor alongside another firm's lead transaction.