13F Filings Explained: How to Track Superinvestors Like Ackman, Tepper, and Howard Marks

In November 2022, Seth Klarman—one of the world's most secretive and successful value investors—filed a 13F showing that Baupost Group had initiated a $450 million position in energy stocks, including a $180 million stake in an overlooked midstream MLP trading at 6x EBITDA. By the time the 13F was public (45 days later), the stock had already rallied 18%. Over the next 12 months, it doubled.

Klarman doesn't give interviews. He doesn't tweet. He doesn't appear on CNBC. But four times a year, he's required by law to disclose exactly what he owns. And savvy investors who track those filings get a window into one of the best investment minds in history.

13F filings provide the only systematic way to track the portfolios of elite institutional investors—superinvestors whose long-term track records vastly exceed market returns. After analyzing thousands of 13Fs over the past decade, I've learned how to separate meaningful signals (new concentrated positions, cluster buying across multiple funds) from noise (index rebalancing, minor trims). This guide will teach you the same framework.

What Is a 13F Filing?

Form 13F is a quarterly report filed by institutional investment managers who exercise investment discretion over $100 million or more in Section 13(f) securities. In plain English: if you manage a big portfolio of U.S. stocks, you have to tell the SEC what you own.

The regulation dates back to 1975, born from post-Watergate reforms designed to increase transparency in financial markets. It requires disclosure of:

• All U.S. exchange-traded equities
• Equity options
• Convertible bonds
• ADRs (American Depositary Receipts)

Notably NOT disclosed:

• International equities held outside the U.S.
• Corporate and government bonds
• Cash positions
• Private investments
• Real estate
• Commodities and futures

13Fs are due 45 days after the end of each calendar quarter. So a position held on December 31 doesn't get disclosed until mid-February. That lag is important—by the time you see the filing, the fund may have already adjusted the position significantly.

Why Track Superinvestors?

Not all institutional investors are worth following. The average hedge fund underperforms the S&P 500 after fees. Many mutual funds are closet indexers. But a small subset of investors—the "superinvestors"—have sustained 15-20 year track records of 12-20%+ annualized returns.

These investors share common traits:

• Long-term focus: They hold positions for years, not quarters
• Concentrated portfolios: Top 10 positions often represent 60-80% of assets
• Deep research capabilities: Teams of analysts conducting primary research
• Willingness to be contrarian: They buy when others panic, hold when others sell

When these investors initiate large new positions, it's worth paying attention. They've done work you haven't, they have access to management you don't, and they're risking enormous capital based on that conviction.

The 25 Superinvestors Worth Tracking

VertData focuses on 25 elite investors with proven long-term records:

Value Investors

• Warren Buffett (Berkshire Hathaway) – The gold standard
• Seth Klarman (Baupost Group) – Deep value, distressed debt specialist
• Li Lu (Himalaya Capital) – Buffett's favorite manager, China expert
• Mohnish Pabrai (Pabrai Investment Funds) – Cloning expert, high concentration
• Guy Spier (Aquamarine Capital) – Value, often clones Buffett
• Howard Marks (Oaktree Capital) – Distressed credit and equity

Activist Investors

• Bill Ackman (Pershing Square) – High-conviction activist
• Carl Icahn (Icahn Enterprises) – Legendary activist, contrarian
• Dan Loeb (Third Point) – Tech-focused activist
• Nelson Peltz (Trian Partners) – Operational improvement focus

Macro and Multi-Strategy

• David Tepper (Appaloosa Management) – Macro, distressed situations
• Stanley Druckenmiller (Duquesne Family Office) – Macro legend, Soros protégé
• Ray Dalio (Bridgewater Associates) – Largest hedge fund globally
• David Einhorn (Greenlight Capital) – Value with short thesis expertise

Growth and Tech

• Chase Coleman (Tiger Global) – Growth equity, tech focus
• Philippe Laffont (Coatue Management) – Tech, internet
• Jim Simons/RenTech (Renaissance Technologies) – Quantitative, though less useful for stock-picking

Special Situations

• Joel Greenblatt (Gotham Asset Management) – Special situations, spin-offs
• Michael Burry (Scion Asset Management) – Contrarian, made famous by "The Big Short"
• David Abrams (Abrams Capital) – Deep value, patient capital

Each investor has a distinct style. Klarman hunts for distressed assets. Ackman takes huge, activist positions in 5-8 stocks. Tepper plays macro inflection points. By tracking multiple investors, you develop pattern recognition for different types of opportunities.

How to Analyze a 13F Filing

When a new 13F hits the SEC EDGAR database, here's the systematic framework I use:

Step 1: Identify New Positions

New positions indicate fresh conviction. The investor analyzed the opportunity, completed due diligence, and deployed capital. Compare this quarter's holdings to last quarter's to spot initiations.

For concentrated investors like Ackman or Burry, every new position is significant. For diversified funds like Bridgewater (hundreds of positions), focus only on positions exceeding 2% of the portfolio.

Step 2: Look for Position Increases

When a superinvestor adds to an existing position, especially by 25%+, it signals continued conviction. They're buying more as they learn more. This is particularly bullish if the stock price has declined since the prior quarter (they're buying weakness).

Step 3: Check Position Sizing

A $50 million position for Baupost (which manages $30 billion) is a rounding error. A $5 billion position represents 16% of the portfolio—massive conviction.

Focus on positions that represent:

• >10% of the fund's portfolio (top 3-5 positions)
• >5% of the target company's market cap (enough to matter)
• >25% of the fund's typical position size (unusually large bet)

Step 4: Calculate Changes in Ownership

If Klarman owned 2.3% of a company last quarter and now owns 4.1%, he nearly doubled his stake. That's more meaningful than a new $10 million position in a company where he owns 0.2%.

Step 5: Cross-Reference Other Superinvestors

This is where the real edge emerges. If Ackman initiates a position and you notice Tepper and Einhorn also own it, you've found convergence—multiple elite investors independently reached the same conclusion.

The Power of Convergence

Convergence—when multiple independent superinvestors own the same stock—is one of the most powerful signals in alternative data. It suggests the stock offers value, a catalyst, or a misunderstood story that professional capital allocators have identified.

Example from VertData's historical convergence analysis:

Four value legends independently concluded that a 12% distribution yield on a critical pipeline MLP was mispriced. They were right.

VertData currently tracks 38 stocks owned by 3+ superinvestors and 7 stocks owned by 5+ superinvestors—these are the highest-conviction ideas in professional value investing today.

Common 13F Analysis Mistakes

Mistake 1: Ignoring the 45-Day Lag

You're seeing stale data. The investor may have added, trimmed, or exited entirely since quarter-end. Use 13Fs as research starting points, not buy triggers.

Mistake 2: Following Every Position

Bridgewater's 13F lists 800+ positions. Most are small, diversified, hedged exposures managed by algorithms. Focus on the concentrated bets (top 10-20 holdings).

Mistake 3: Treating All Investors Equally

A new Ackman position (who runs $12 billion in 8 stocks) means infinitely more than a new position from a $500 million fund with 150 holdings. Weight your analysis by concentration and track record.

Mistake 4: Ignoring Portfolio Context

If Klarman's portfolio is 40% cash, 30% bonds (not disclosed in 13F), and 30% equities, his equity positions are less aggressive than they appear. Try to understand the full portfolio through investor letters, interviews, and conference presentations.

Mistake 5: Forgetting Confidential Treatment

Investors can request confidential treatment while building positions. When confidentiality expires, the "new" position revealed in the 13F may actually be months old. Check for confidential treatment requests in the 13F header.

Building Your Superinvestor Watchlist

Here's my quarterly workflow:

1. 13F deadline hits (45 days after quarter-end): Set calendar reminders for mid-Feb, mid-May, mid-Aug, mid-Nov
2. Pull filings immediately: Use SEC EDGAR or VertData's auto-ingestion (filings appear within minutes of publication)
3. Scan for new positions and large increases across your tracked investors
4. Run convergence analysis: Which stocks appear in 3+ portfolios?
5. Cross-reference with insider buying: Do Form 4 filings show insider purchases at these companies?
6. Check short interest: Is the stock heavily shorted despite superinvestor ownership?
7. Create research queue: Top 10-15 names flagged for deeper analysis
8. Read earnings transcripts and investor letters for those names
9. Make investment decisions based on your own analysis, using 13F data as validation

This process takes 2-3 hours per quarter and generates a curated list of institutional-quality ideas you wouldn't have found independently.

Advanced Technique: Cloning Strategies

Some investors specialize in "cloning"—replicating superinvestor portfolios systematically. Mohnish Pabrai has written extensively about this approach, arguing that piggybacking on better investors' research is rational and effective.

A simple cloning strategy:

1. Select 5-10 concentrated value investors (Buffett, Klarman, Li Lu, Pabrai, Ackman)
2. Each quarter, buy their new positions or significant increases (>25%)
3. Hold for minimum 1 year (match their time horizon)
4. Rebalance quarterly based on new 13F data

Backtested academic research on cloning strategies shows they outperform the S&P 500 by 2-4% annually, though with higher volatility and significant tracking error.

The weakness: You're always 45-90 days behind, you don't understand the thesis, and you have no idea when to sell. I prefer using 13Fs as research filters rather than mechanical buy signals.

Real-World Case Study: Bill Ackman's Netflix Call

Q1 2022 13F (filed May 2022): Ackman's Pershing Square initiated a $1.1 billion position in Netflix (NFLX) at an average price around $375/share. This was major news—Ackman taking a 3 million share stake representing ~10% of his portfolio.

What happened: Within days of the 13F publication, Netflix reported disastrous subscriber numbers. The stock cratered to $190. Ackman sold the entire position at a massive loss within one month.

The lesson: Even superinvestors are wrong frequently. Ackman misread Netflix's competitive position and subscriber saturation. Following his 13F blindly would have resulted in a 50% loss in weeks.

This reinforces the critical rule: Use 13Fs as research ideas, not buy signals. Validate the thesis yourself. Understand the risks. Make your own decision.

The Bottom Line

13F filings provide unparalleled transparency into the portfolios of the world's best investors. When used correctly—focused on concentrated portfolios, new positions, convergence signals, and combined with your own fundamental analysis—they're a powerful tool for idea generation.

The key is selectivity. Don't follow every fund. Don't buy every new position. Focus on the 10-15 investors whose style, track record, and concentration level make their decisions meaningful. Then use their 13Fs as a research filter that narrows the 10,000+ investable stocks down to 20-30 worth investigating each quarter.

Combine 13F analysis with insider buying (Form 4), short interest data, and your own fundamental research. When Klarman initiates a position, insiders are buying, shorts are covering, and the stock trades at 10x earnings—you've found something worth owning.

That's how professional fundamental investors use alternative data: not as a replacement for analysis, but as a force multiplier that directs attention to the most promising opportunities.