William Harnisch Portfolio March 2026 - Top Holdings & 13F Analysis

About William Harnisch and PECONIC PARTNERS LLC

William Harnisch is the portfolio manager at PECONIC PARTNERS LLC, one of the closely tracked institutional investors in our database. Every quarter, institutional investment managers with over $100 million in assets under management are required to file a 13F report with the SEC, disclosing their long equity positions. These filings give retail investors a rare window into how professional money managers are allocating capital.

As of March 2026, William Harnisch's 13F portfolio contains 15 positions with a disclosed market value of approximately $4.21 billion. This analysis covers their top holdings, recent portfolio changes, and key investment themes.

Over the past year, William Harnisch's portfolio has delivered a +51.7% return, significantly outperforming the broader market.

William Harnisch's Top 10 Holdings — March 2026

The following table shows William Harnisch's largest disclosed stock positions ranked by portfolio weight as reported in the most recent 13F filing. These represent the highest-conviction bets in the portfolio:

Data sourced from SEC 13F filings. Holdings reflect disclosed long equity positions. Options and short positions may not be reflected.

Portfolio Strategy & Concentration Analysis

William Harnisch's investment approach reflects a highly concentrated portfolio strategy. The top position, QUANTA SCVS INC (PWR), represents 5022.8% of the total portfolio, while the top 5 holdings collectively account for 9572.8% of disclosed assets.

During this period, William Harnisch initiated 6 new positions — a signal that they identified compelling entry points in new opportunities. New positions often represent the highest-conviction ideas as managers dedicate fresh capital to them.

Additionally, William Harnisch increased stakes in 4 existing positions, a sign of growing conviction in those holdings.

New Positions Added in March 2026

The following stocks represent new entries in William Harnisch's portfolio — positions that were not present in the prior quarter's 13F filing. New positions are closely watched by investors as they signal fresh conviction:

Best Performing Holdings in William Harnisch's Portfolio

Based on available performance data, the following positions have been the strongest contributors to William Harnisch's portfolio returns:

Understanding William Harnisch's 13F Filing

Despite these limitations, 13F filings remain one of the best public sources of information on how professional investors are positioning their portfolios. Use this data as one input among many, alongside your own research and risk tolerance.

How Retail Investors Can Use This Information

Following institutional 13F filings like William Harnisch's can provide valuable investment insights — but it's important to use this information correctly:

• Identify high-conviction ideas: Large positions and new entries signal where managers have the strongest conviction.
• Spot emerging themes: Cross-portfolio analysis reveals sector rotations and macro themes playing out across institutional money.
• Validate your own research: If an investor you respect owns a stock you're analyzing, that can reinforce your thesis.
• Track changes over time: Watching a manager increase or decrease positions over multiple quarters shows conviction trends.
• Don't blindly copy trades: Remember that institutional investors have different time horizons, risk tolerances, and information than retail investors.

You can track William Harnisch's complete portfolio in real-time on Insider Edges, including historical holdings, sector breakdown, and performance data.

Other Top Investors to Follow

If you track William Harnisch's portfolio, you may also be interested in following these other closely watched institutional investors: