Compare 13F Filings Side by Side

Introduction: Why Compare 13F Filings?

Institutional investors file 13F forms every quarter to disclose their holdings. But a single 13F snapshot tells only part of the story. The real insight comes from comparing two filings side by side—spotting what changed, what stayed the same, and what those changes reveal about an investor’s strategy.

Whether you’re tracking a specific hedge fund or analyzing sector trends, learning to compare filings systematically will help you identify portfolio shifts before they become obvious to the broader market. This guide walks you through the process step by step.

What You’ll Learn

How to access and load two filings for comparison
What to look for when comparing holdings
How to spot new positions, exits, and size changes
Understanding amendments and why they matter
Practical walkthrough with a real filer example

Step 1: Find and Load Two Filings

Start by navigating to a filer’s detail page. On 13F Insight, you can search for any institutional investor by name or CIK number. For example, let’s use Berkshire Hathaway, one of the most-watched institutional investors.

Once on the filer page, you’ll see a list of their recent 13F filings. Each filing shows:

Report Date — The quarter-end date (e.g., December 31, 2025)
Filing Date — When the form was submitted to the SEC
Total Value — The portfolio’s total market value at that date
Holdings Count — Number of positions held

Click on the most recent filing to view its holdings. Then, open the previous quarter’s filing in a new tab or window so you can compare them side by side.

Step 2: Compare Total Portfolio Size

Before diving into individual positions, compare the overall portfolio metrics:

Total AUM (Assets Under Management) — Did the portfolio grow or shrink? A 10% increase signals confidence; a 20% decrease might indicate redemptions or a strategic pivot.
Holdings Count — More positions = diversification; fewer positions = concentration. A drop from 50 to 40 holdings suggests the investor is consolidating.
Sector Allocation — Did the investor shift from tech to healthcare? From large-cap to small-cap?

These macro-level changes set the context for what you’ll see in individual positions.

Step 3: Identify New Positions (Buys)

New positions are stocks that appear in the current filing but not in the previous one. These are the most exciting signals because they represent fresh conviction.

What to look for:

Position Size — Is it a small experimental position (0.1% of portfolio) or a major bet (2%+)? Larger positions signal stronger conviction.
Sector — Does the new position fit the investor’s existing strategy, or is it a new thematic bet?
Timing — Did the investor buy during a market dip or at all-time highs? Check the stock’s price history around the filing date.

For example, if Berkshire Hathaway initiates a new position in NVIDIA (NVDA), that’s a significant signal given their historical focus on mature, profitable companies.

Step 4: Spot Complete Exits

Complete exits are positions that existed in the previous filing but are gone in the current one. These can be equally revealing as new buys.

What to consider:

Reason for Exit — Did the stock underperform? Did the investor’s thesis change? Did they take profits after a big run-up?
Timing — If the exit happened before a major market correction, it suggests good timing. If after, it might indicate a thesis change.
Position Size — Exiting a 3% position is more significant than exiting a 0.1% position.

Exits often reveal more about an investor’s conviction than buys, because they show what the investor no longer believes in.

Step 5: Analyze Size Changes (Adds and Trims)

Most positions don’t disappear entirely—they grow or shrink. These partial changes are where you’ll find the most nuanced signals.

Categories of size changes:

Significant Adds (>50% increase) — The investor is doubling down. This is conviction.
Modest Adds (10-50% increase) — The investor likes the position but isn’t going all-in.
Modest Trims (10-50% decrease) — Profit-taking or rebalancing, not a thesis change.
Significant Trims (>50% decrease) — The investor is losing conviction or raising cash.

Compare these changes to the stock’s performance. If an investor adds to a stock that’s down 20%, that’s a strong buy signal. If they trim a stock that’s up 50%, that’s profit-taking.

Step 6: Understand Amendments vs. Original Filings

13F filings can be amended. You might see a filing labeled “13F-HR” (original) or “13F-HR/A” (amended). Here’s what you need to know:

Original Filing (13F-HR) — The first submission for a quarter. It’s usually filed within 45 days of quarter-end.
Amended Filing (13F-HR/A) — A correction to the original. Amendments happen when the investor discovers errors in holdings, valuations, or share counts.
Which One to Use? — Always use the most recent amendment. On 13F Insight, we automatically show you the latest version, so you don’t have to worry about this.

Why amendments matter: Large amendments can signal data quality issues or, in rare cases, intentional misreporting. If an amendment changes a major position by 10%+, it’s worth noting.

Step 7: Practical Walkthrough—Comparing Two Real Filings

Let’s walk through a concrete example. Suppose you’re comparing Berkshire Hathaway’s Q4 2025 filing to Q3 2025.

Step 1: Load both filings

Visit Berkshire’s filer page and open Q4 2025 and Q3 2025 filings in separate tabs.

Step 2: Compare totals

Q4 2025: $800B AUM, 50 holdings
Q3 2025: $780B AUM, 52 holdings

Observation: AUM grew 2.6%, but holdings count dropped by 2. This suggests consolidation—Berkshire exited some smaller positions and concentrated capital in core holdings.

Step 3: Spot new positions

Scanning the Q4 filing, you notice Microsoft (MSFT) appears for the first time with a 1.2% portfolio weight. This is a significant new position for Berkshire.

Step 4: Identify exits

A small position in a regional bank that was 0.3% in Q3 is gone in Q4. This aligns with Berkshire’s known skepticism about regional banking.

Step 5: Analyze size changes

Apple (AAPL) grew from 45% to 48% of the portfolio—a 6.7% increase. This is a significant add to Berkshire’s largest position, signaling continued conviction.

Step 6: Check for amendments

Both filings are original (13F-HR), so no corrections to account for.

Conclusion: Berkshire is consolidating around core tech positions (Apple, Microsoft) while exiting smaller, non-core holdings. This suggests a shift toward concentration in mega-cap tech.

Step 8: Common Misconceptions

Misconception 1: “A new position means the investor will hold it forever.”

Reality: New positions are often experimental. Many are trimmed or exited within 1-2 quarters. Track the position over multiple filings to see if it becomes core or remains tactical.

Misconception 2: “A trim means the investor lost conviction.”

Reality: Trims often reflect profit-taking or rebalancing, not thesis changes. A 20% trim of a position that’s up 100% is healthy portfolio management, not a red flag.

Misconception 3: “Amendments are rare and unimportant.”

Reality: Amendments happen in roughly 10-15% of filings. Most are minor, but some correct significant errors. Always check if a filing you’re analyzing has been amended.

FAQ: Questions You Might Have

Q: How often should I compare filings?

A: Quarterly is standard, since 13F filings are quarterly. If you’re tracking a specific investor, compare each new filing to the previous one. For broader market analysis, compare year-over-year (same quarter, different years) to filter out seasonal noise.

Q: What if a position size changed but the stock price also moved significantly?

A: Good question. A position’s value can change due to two factors: (1) the investor buying/selling shares, or (2) the stock price moving. 13F filings show the number of shares held, so you can calculate the true change. If shares increased 10% but the stock price fell 5%, the investor definitely added to the position.

Q: Can I use 13F comparisons to predict stock price movements?

A: Not directly. 13F filings are backward-looking (they show positions as of quarter-end) and are filed 45 days later. By the time you see a new position, the market may have already priced it in. However, comparing filings helps you understand institutional conviction and can inform longer-term investment theses.

Q: What if an investor holds a stock through a subsidiary or fund?

A: 13F filings show direct holdings only. If an investor holds a stock indirectly (e.g., through a fund they own), it won’t appear on their 13F. This is a limitation of the form, not a flaw in your analysis.

Q: How do I know if a position is a hedge vs. a core holding?

A: You can’t tell from the 13F alone. A small position could be a hedge or an experimental bet. Track the position over multiple quarters: if it stays small and stable, it’s likely a hedge. If it grows, it’s becoming core. If it disappears, it was tactical.

Next Steps

Now that you understand how to compare filings, try it yourself. Pick a filer you’re interested in—maybe Berkshire Hathaway, a tech-focused fund, or a value investor—and compare their last two quarterly filings. Look for the patterns we discussed: new positions, exits, size changes, and sector shifts.

As you practice, you’ll develop intuition for what different changes signal. Over time, comparing filings becomes a powerful tool for understanding institutional investor strategy and spotting emerging market trends.

For more on how to interpret 13F data, check out our other guides on what a 13F filing is and how to read holdings data.