New Mountain Capital, L.L.C. — 13F Holdings & Portfolio
CIK 1407718 · latest 13F-HR filed 2026-08-14
New Mountain Capital, L.L.C. manages $138.6M in 13F-reported U.S. long-equity assets across 1 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are AVTR (100.00%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 0 new positions and exited 0; 1 existing position rose in reported value and 0 fell.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
Long-equity book
Distinct positions
Filed 2026-08-14
vs 2026-03-31
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
Portfolio map
Q2 26Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.
Sector mix
% of 13F valueSectors from each company's SIC code; funds and ETFs grouped separately.
Biggest buys and sells
Q1 26 → Q2 26Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.
13F assets and positions
4 quartersTotal reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.
Top positions over time
reported valueThe eight largest current positions, valued at each quarter end.
Concentration
top 10 = 100%Cumulative share of the portfolio held in the largest N positions.
As of the firm’s regulatory filing dated Mar 30, 2026.
48TH FL.
NEW YORK, NY 10019
| Name | Title / Status | Ownership | Type |
|---|---|---|---|
| KLINSKY, STEVEN, BRUCE Control | FOUNDER, CHIEF EXECUTIVE OFFICER since Jul 1999 | 50–75% | Individual |
| NEW MOUNTAIN CAPITAL GROUP, L.P. Control | MEMBER since Jul 1999 | 75% or more | Domestic Entity |
| WEINSTEIN, ADAM, BRETT Control | PRESIDENT, MANAGING DIRECTOR, CHIEF OPERATING OFFICER since Jan 2015 | Less than 5% | Individual |
| HARTSWELL, JOSEPH, WESLEY | MANAGING DIRECTOR AND CHIEF COMPLIANCE OFFICER since Aug 2015 | Less than 5% | Individual |
| Hausler, John, Michael | MANAGING DIRECTOR AND CHIEF FINANCIAL OFFICER since Dec 2025 | Less than 5% | Individual |
| KLINSKY, STEVEN, BRUCE Control Indirect owner via NM HOLDINGS GP, L.L.C. | MANAGING MEMBER since Oct 2018 | 50–75% | Individual |
| KLINSKY, STEVEN, BRUCE Control Indirect owner via NM PARTNERS MANAGER HOLDINGS, L.P. | LIMITED PARTNER since Oct 2018 | 50–75% | Individual |
| NM HOLDINGS GP, L.L.C. Control Indirect owner via NEW MOUNTAIN CAPITAL GROUP, L.P. | GENERAL PARTNER since Oct 2018 | General partner, trustee or manager | Domestic Entity |
| NM HOLDINGS GP, L.L.C. Control Indirect owner via NM PARTNERS MANAGER HOLDINGS, L.P. | GENERAL PARTNER since Oct 2018 | General partner, trustee or manager | Domestic Entity |
| NM PARTNERS MANAGER HOLDINGS, L.P. Control Indirect owner via NEW MOUNTAIN CAPITAL GROUP, L.P. | LIMITED PARTNER since Oct 2018 | 75% or more | Domestic Entity |
Ownership & leadership changes · 8 filings with changes since Feb 14, 2012
From the firm’s regulatory filings, newest first. Dates are filing dates: a filing that no longer lists someone does not say when they left.
- AddedHausler, John, Michael · MANAGING DIRECTOR AND CHIEF FINANCIAL OFFICER · Less than 5%
- ChangedWEINSTEIN, ADAM, BRETT · title MANAGING DIRECTOR, CHIEF FINANCIAL OFFICER → PRESIDENT, MANAGING DIRECTOR, CHIEF OPERATING OFFICER
- ChangedKLINSKY, STEVEN, BRUCE · ownership 75% or more → 50–75%
- ChangedKLINSKY, STEVEN, BRUCE · indirect via NM HOLDINGS GP, L.L.C.: ownership 75% or more → 50–75%
- ChangedKLINSKY, STEVEN, BRUCE · indirect via NM PARTNERS MANAGER HOLDINGS, L.P.: ownership 75% or more → 50–75%
- ChangedNEW MOUNTAIN CAPITAL GROUP, L.P. · title LIMITED PARTNER → MEMBER
- No longer listedKLINSKY, STEVEN, BRUCE · MANAGING MEMBER · 75% or more · indirect via NEW MOUNTAIN CAPITAL GROUP, L.L.C. · control person · listed since Mar 2004
- No longer listedNEW MOUNTAIN CAPITAL GROUP, L.L.C. · MANAGING MEMBER · 75% or more · control person · listed since Mar 2004
- AddedKLINSKY, STEVEN, BRUCE · MANAGING MEMBER · 75% or more · indirect via NM HOLDINGS GP, L.L.C. · control person
- AddedKLINSKY, STEVEN, BRUCE · LIMITED PARTNER · 75% or more · indirect via NM PARTNERS MANAGER HOLDINGS, L.P. · control person
- AddedNEW MOUNTAIN CAPITAL GROUP, L.P. · LIMITED PARTNER · 75% or more · control person
- AddedNM HOLDINGS GP, L.L.C. · GENERAL PARTNER · General partner, trustee or manager · indirect via NEW MOUNTAIN CAPITAL GROUP, L.P. · control person
- AddedNM HOLDINGS GP, L.L.C. · GENERAL PARTNER · General partner, trustee or manager · indirect via NM PARTNERS MANAGER HOLDINGS, L.P. · control person
- AddedNM PARTNERS MANAGER HOLDINGS, L.P. · LIMITED PARTNER · 75% or more · indirect via NEW MOUNTAIN CAPITAL GROUP, L.P. · control person
- No longer listedBOSCO, PAULA, ANN · MANAGING DIRECTOR, CCO & CHIEF REGULATORY COUNSEL · Less than 5% · listed since Jan 2011
- AddedHARTSWELL, JOSEPH, WESLEY · MANAGING DIRECTOR AND CHIEF COMPLIANCE OFFICER · Less than 5%
- No longer listedCOLLINS, ADAM, JEREMY · MANAGING DIRECTOR, CO-CHIEF FINANCIAL OFFICER · Less than 5% · control person · listed since Sep 2001
- No longer listedLONDAL, DOUGLAS, FRED · PRESIDENT, CHIEF OPERATING OFFICER, MANAGING DIRECTOR · Less than 5% · control person · listed since Apr 2013
- ChangedWEINSTEIN, ADAM, BRETT · title MANAGING DIRECTOR, CO-CHIEF FINANCIAL OFFICER → MANAGING DIRECTOR, CHIEF FINANCIAL OFFICER
- AddedLONDAL, DOUGLAS, FRED · PRESIDENT, CHIEF OPERATING OFFICER, MANAGING DIRECTOR · Less than 5% · control person
- AddedWEINSTEIN, ADAM, BRETT · MANAGING DIRECTOR, CO-CHIEF FINANCIAL OFFICER · Less than 5% · control person
- ChangedBOSCO, PAULA, ANN · title CHIEF COMPLIANCE OFFICER → MANAGING DIRECTOR, CCO & CHIEF REGULATORY COUNSEL
- ChangedCOLLINS, ADAM, JEREMY · title CHIEF FINANCIAL OFFICER → MANAGING DIRECTOR, CO-CHIEF FINANCIAL OFFICER
- ChangedKLINSKY, STEVEN, BRUCE · ownership Less than 5% → 75% or more
- ListedBOSCO, PAULA, ANN · CHIEF COMPLIANCE OFFICER · Less than 5%
- ListedCOLLINS, ADAM, JEREMY · CHIEF FINANCIAL OFFICER · Less than 5% · control person
- ListedKLINSKY, STEVEN, BRUCE · FOUNDER, CHIEF EXECUTIVE OFFICER · Less than 5% · control person
- ListedKLINSKY, STEVEN, BRUCE · MANAGING MEMBER · 75% or more · indirect via NEW MOUNTAIN CAPITAL GROUP, L.L.C. · control person
- ListedNEW MOUNTAIN CAPITAL GROUP, L.L.C. · MANAGING MEMBER · 75% or more · control person
Quarter-over-quarter changes
Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.
New Mountain Capital, L.L.C. Holdings (2026-06-30)
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | AVANTOR INC | AVTR | 05352A100 | $138.6M | 100.00% | 14,000,000 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-14 | $138.6M | 1 | 0001172661-26-003453 |
| 2026-03-31 | 2026-05-13 | $109.8M | 1 | 0001172661-26-001765 |
| 2025-12-31 | 2026-02-17 | $160.4M | 1 | 0001172661-26-000966 |
| 2025-09-30 | 2025-11-14 | $174.7M | 1 | 0001172661-25-004866 |
48TH FLOOR
NEW YORK, NY 10019