Q3 2026 13F · SEC CIK 830588
Summit Partners L P
Hedge fundFiled 2026-10-29 for Q3 2026. Open the filing ↗ · All SEC filings ↗
- Reported 13F value
- $490.9M
- Reported positions
- 5
- Top holdings a year, 3 yrs
- -6.0%
- Assets under management
- $42.0B
Summit Partners L P is a hedge fund that reported 5 positions worth $490.9M in its Q3 2026 13F, filed 2026-10-29. Its largest holdings were Klaviyo Inc (KVYO, 44.4%), Lifestance Health Group Inc (LFST, 40.7%), A K A Brands Hldg Corp (AKA, 13.4%). A portfolio copying its top holdings returned -6.0% a year over the last 3 years, against 20.4% for the S&P 500.
Summit Partners L P holdings all 5 positions.
Weights are shares of the filer's total reported 13F value, compared with Q2 2026. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.
| Stock | % of 13F value | Share change | Reported value |
|---|---|---|---|
| KVYOKlaviyo Inc | 44.4% | -26.5% | $217.9M |
| LFSTLifestance Health Group Inc | 40.7% | -28.7% | $200.0M |
| AKAA K A Brands Hldg Corp | 13.4% | +0.0% | $65.9M |
| ATENA10 Networks Inc | 1.1% | +0.0% | $5.4M |
| MTSIMacom Tech Solutions Hldgs I | 0.3% | +0.0% | $1.7M |
What Summit Partners L P bought and sold in Q3 2026, against Q2 2026.
New positions
No new positions among the largest holdings.
Added to
No position grew by more than 5%.
Reduced
- LFST Lifestance Health Group Inc-28.7% shares
- KVYO Klaviyo Inc-26.5% shares
Sold out
Nothing sold out.
Share counts compared with the Q2 2026 13F; a split also changes share counts.
How the holdings did against the S&P 500.
- 1 year
- -6.8% /yr
- S&P 500 +20.1%
- 3 years
- -6.0% /yr
- S&P 500 +20.4%
- 5 years
- -16.1% /yr
- S&P 500 +11.6%
A portfolio of the filer's 20 largest 13F positions, weighted by value, bought the trading day after each 13F was filed and held until the next one was: what copying this filer could have earned. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.
Reported 13F value by quarter.
| Quarter | 13F value | Positions |
|---|---|---|
| Q3 2026 | $490.9M | 5 |
| Q2 2026 | $608.9M | 5 |
| Q1 2026 | $670.2M | 7 |
| Q4 2025 | $1.1B | 8 |
| Q3 2025 | $924.3M | 8 |
| Q2 2025 | $1.4B | 7 |
| Q1 2025 | $1.6B | 9 |
| Q4 2024 | $2.2B | 8 |
| Q3 2024 | $2.2B | 9 |
| Q2 2024 | $1.7B | 9 |
| Q1 2024 | $1.8B | 10 |
| Q4 2023 | $2.7B | 11 |
Questions about Summit Partners L P's portfolio
What stocks does Summit Partners L P own?
Summit Partners L P's latest 13F, for Q3 2026 and filed Oct 29, 2026, lists 5 positions worth $490.9M. The largest are Klaviyo Inc (KVYO) at 44.4%, Lifestance Health Group Inc (LFST) at 40.7%, A K A Brands Hldg Corp (AKA) at 13.4%, A10 Networks Inc (ATEN) at 1.1% and Macom Tech Solutions Hldgs I (MTSI) at 0.3%.
What did Summit Partners L P buy last quarter?
Summit Partners L P opened no new positions and grew none by more than 5% among its largest holdings in Q3 2026.
What did Summit Partners L P sell last quarter?
In Q3 2026, Summit Partners L P Lifestance Health Group Inc (LFST) (-28.7% shares) and Klaviyo Inc (KVYO) (-26.5% shares), compared with its Q2 2026 filing.
How has Summit Partners L P's portfolio performed?
A portfolio copying Summit Partners L P's 20 largest 13F holdings each quarter, from the day each filing was public, returned -6.0% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: -6.8% against +20.1%. Over 5 years: -16.1% a year against +11.6%.
When is Summit Partners L P's next 13F filing due?
13F filings are due 45 days after each quarter ends. Summit Partners L P's filing for the quarter ending Dec 31, 2026 is due by Feb 14, 2027; this page updates the day after it is published.
How much money does Summit Partners L P manage?
Summit Partners L P reported $42.0B of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $490.9M.