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Sirios Capital Management, L.P.
John F. Brennan, Jr. · Hedge Fund · Long/Short Equity
Founded in 1999 by John F. Brennan, Jr. and based in Boston, Sirios Capital Management, L.P. is a fundamental, research-driven investment firm specializing in long/short equity and concentrated long-only strategies. The firm primarily invests in mid- to large-cap companies across diverse global sectors, including consumer, energy, healthcare, and technology. Sirios provides discretionary investment advisory services to institutional clients such as endowments, foundations, and high-net-worth individuals, as well as managing private funds and UCITS vehicles. The firm is recognized for its bottom-up investment process and sector-specific expertise, focusing on identifying mispriced growth-oriented securities to deliver long-term capital appreciation and risk-adjusted returns.
Simulated Performance
| Metric | Value |
|---|---|
| Total return | +34.5% |
| YTD return | +23.6% |
| Sharpe ratio | 3.44 |
| Win rate | 49% |
| AUM | $0.7B |
| Inception | Oct 1, 2025 |
| Updated | Sep 21, 2026 |
Institution Status
| Field | Value |
|---|---|
| AUM | $0.7B |
| Turnover | Low (<15%) |
| Avg holding | 18 Months |
| Inception | Oct 1, 2025 |
| Website | https://www.sirioslp.com |
Current Holdings
Updated on Sep 21, 2026.
| Ticker | Name | Portfolio % | Return |
|---|---|---|---|
| GEV | GE Vernova LLC | 19.4% | +28.9% |
| ONTO | Onto Innovation Inc | 7.6% | +15.2% |
| TSM | Taiwan Semiconductor Manufacturing | 7.1% | +46.0% |
| AMZN | Amazon.com Inc | 6.6% | +11.7% |
| AMD | Advanced Micro Devices Inc | 6.3% | +16.7% |
| DXCM | DexCom Inc | 5.7% | +27.0% |
| GOOGL | Alphabet Inc Class A | 5.5% | -3.2% |
| HEI | Heico Corporation | 4.6% | -3.5% |
| GMED | Globus Medical | 4.5% | +6.7% |
| WFC | Wells Fargo & Company | 4.3% | +6.3% |
| UNF | Unifirst Corporation | 4.2% | +0.2% |
| CG | Carlyle Group Inc | 4.0% | -20.2% |
| UNP | Union Pacific Corporation | 2.9% | +3.2% |
| GPN | Global Payments Inc | 2.8% | +7.0% |
| CLH | Clean Harbors Inc | 2.7% | +23.5% |
| ODFL | Old Dominion Freight Line Inc | 2.6% | +3.2% |
| ALC | Alcon AG | 2.4% | -7.0% |
| ADI | Analog Devices Inc | 2.3% | +8.6% |
| CARR | Carrier Global Corp | 2.2% | -21.7% |
| VST | Vistra Energy Corp | 2.1% | +2.4% |
Recent activity
| Date | Action | Ticker | Weight |
|---|---|---|---|
| Sep 21, 2026 | BUY | GOOGL | 5.5% → 5.5% |
| Sep 21, 2026 | BUY | VST | 2.1% → 2.1% |
| Sep 21, 2026 | BUY | UNF | 4.2% → 4.2% |
| Sep 21, 2026 | SELL | GEV | 19.4% → 19.4% |
| Sep 21, 2026 | SELL | ADI | 2.3% → 2.3% |
Investment Style Analysis
Sirios Capital Management, L.P. is widely recognized for employing a Long/Short Equity strategy. As of Sep 21, 2026, the firm oversees approximately $0.7B in assets under management (AUM). The portfolio demonstrates a clear preference for the Specialty Industrial Machinery and Semiconductors sectors, reflecting a high-conviction approach to capital allocation.
Recent Market Moves
During the latest rebalancing period ending Sep 21, Sirios Capital Management, L.P. made a significant move by increasing exposure to GOOGL. This adjustment aligns with the fund's dynamic approach to risk management and capital deployment in current market conditions.
Investment Philosophy
Sirios Capital Management employs a fundamental, research-intensive approach to identify investment opportunities and potential short-sale candidates, generally focusing on medium to large capitalization growth companies. The firm's core strategy combines the flexibility of a multi-sector, diversified long/short hedge fund with the depth of individual sector specialization. Investment analysts focus on broad sectors such as Consumer, Healthcare, and Technology, conducting company-by-company research to find firms with strong earnings potential and attractive valuations. For short positions, the firm targets stocks with deteriorating fundamentals and excessive valuations. This bottom-up process is designed to outperform broad market indices over the long term while managing risk through position sizing and moderate gross exposure.
Disclaimer
The content provided on this page, including the simulated portfolio performance, holdings analysis, and AI-generated insights, is for informational and educational purposes only. It does not constitute financial advice, investment recommendations, or an offer to buy or sell any securities. All data is derived from historical SEC 13F filings and other public disclosures, which have a reporting lag. The "Simulated Performance" is a hypothetical reconstruction based on past disclosures and does not represent the actual returns of the institution. Past performance is not indicative of future results. Tritonix.ai is not affiliated with Sirios Capital Management, L.P..
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Frequently asked questions
How is the simulated portfolio for Sirios Capital Management, L.P. constructed?
This simulation is powered by Tritonix AI using official SEC filings. We focus on the "Best Ideas" by filtering for only the Top 20 largest holdings and rebalancing them to 100%. The simulation tracks performance starting from Oct 1, 2025. Our AI monitors for updates every Monday to capture major shifts. This concentrated approach highlights the manager's true stock-picking skill and mirrors their actual investment returns.
What is Sirios Capital Management, L.P.'s largest holding?
As of the latest filing, Sirios Capital Management, L.P.'s top position is GE Vernova LLC (GEV), representing 19.4% of the portfolio. This reflects a high-conviction bet by the institution.
What is Sirios Capital Management, L.P.'s historical performance and risk profile?
Our simulation indicates a total return of +34.5% with a win rate of 49%. Notably, the portfolio maintains a Sharpe Ratio of 3.44, suggesting an exceptional level of risk-adjusted returns compared to the broader market.
What sectors does Sirios Capital Management, L.P. primarily invest in?
Sirios Capital Management, L.P. has a strong preference for the Specialty Industrial Machinery sector, which makes up 19.4% of their disclosed assets. The portfolio also has exposure to Semiconductors, indicating a specific thematic focus.
Is Sirios Capital Management, L.P.'s portfolio concentrated or diversified?
Sirios Capital Management, L.P. runs a moderately concentrated portfolio with 20 disclosed positions. The top 3 holdings alone account for 34.2% of the total portfolio weight, suggesting a strategy that favors broader market exposure.
How has Sirios Capital Management, L.P. performed in 2026?
Our AI-simulated model portfolio for Sirios Capital Management, L.P. tracks a Year-to-Date (YTD) return of +23.6%. This metric helps investors gauge the institution's effectiveness in the current market environment.
Does John F. Brennan, Jr. manage Sirios Capital Management, L.P. directly?
Yes, John F. Brennan, Jr. serves as the key portfolio manager for Sirios Capital Management, L.P., overseeing the investment strategy and final capital allocation decisions.