Four times a year, the investment research world goes through a predictable flurry of activity. Thousands of hedge fund and institutional investor disclosures drop within a narrow window, analysts pore over the data, and financial media fills up with headlines about what Warren Buffett bought, what Michael Burry sold, and which stocks the smart money is moving into.
This period is known informally as 13F season. If you track superinvestor portfolios as part of your research process, understanding when it happens and how to use it is essential.
What Is 13F Season?
13F season refers to the roughly two-to-three week window following each quarterly 13F filing deadline, during which institutional investors must submit their equity holdings disclosures to the SEC. Because thousands of managers file within this window — often clustered around the deadline itself — a large amount of portfolio data becomes available in a short period.
The term is not official SEC terminology. It is investing community shorthand, similar to "earnings season," that describes the predictable quarterly rhythm of institutional disclosure activity.
For individual investors who track what major fund managers own, 13F season is among the most information-rich periods of the quarter. For a fuller explanation of what 13F filings are and what they contain, see our guide to SEC Form 13F.
When Is 13F Season? The 2026 Schedule
13F filings are due 45 days after the end of each calendar quarter. The four filing deadlines in 2026 are:
| Quarter | Quarter end date | Filing deadline | Data reflects | |---|---|---|---| | Q4 2025 | December 31, 2025 | February 14, 2026 | Holdings as of Dec 31 | | Q1 2026 | March 31, 2026 | May 15, 2026 | Holdings as of Mar 31 | | Q2 2026 | June 30, 2026 | August 14, 2026 | Holdings as of Jun 30 | | Q3 2026 | September 30, 2026 | November 14, 2026 | Holdings as of Sep 30 |
In practice, many managers file several days before the deadline — particularly larger funds with established compliance teams. This means new disclosures begin appearing in the week before each deadline, then surge on the deadline date itself.
The most active research period — what most investors mean when they say "13F season" — runs from roughly the filing deadline through the following week or two, as analysts and investors work through the data.
Why 13F Season Gets So Much Attention
The reason 13F season generates consistent attention comes down to the nature of the managers filing. Among the thousands of institutional investors required to disclose quarterly holdings, a small group commands disproportionate interest:
Warren Buffett — Berkshire Hathaway. Arguably the most-watched 13F in the world. Any new position, significant addition, or complete exit by Berkshire generates immediate media coverage and analyst commentary.
Bill Ackman — Pershing Square Capital Management. Known for highly concentrated, often activist positions. Ackman's filings reveal a small number of high-conviction bets that frequently attract significant attention.
Michael Burry — Scion Asset Management. Famous for his prescient call on the 2008 housing crisis. Burry's filings are small and concentrated — often just a handful of positions — which makes each one significant.
Seth Klarman — Baupost Group. One of the most respected value investors of his generation and author of the widely read Margin of Safety. Klarman rarely speaks publicly, which makes his quarterly filings one of the few windows into his thinking.
David Tepper — Appaloosa Management. Known for bold macro-driven bets and a willingness to take large, concentrated positions. His sector moves are closely watched as indicators of broader market views.
When these managers file, their new positions, additions, and exits are immediately analyzed and reported across financial media, investment research platforms, and social channels. This concentration of information in a short window is what gives 13F season its distinctive character.
How to Prepare for 13F Season
For investors who actively incorporate superinvestor data into their research, a small amount of preparation before each 13F season makes the process significantly more productive.
Know which managers you follow
The volume of filings during 13F season can be overwhelming if you try to track everyone. Define in advance which managers are most relevant to your investment philosophy. Value investors may focus on Buffett, Klarman, and Tepper. Growth-oriented investors might prioritize different managers. Quality-focused investors might follow Terry Smith, Chuck Akre, or similar.
A focused list of ten to fifteen managers produces better research output than attempting to synthesize hundreds of filings.
Know what changed last quarter
Before new filings arrive, review the prior quarter's data for your key managers. Refresh your memory of what they held, what they had been adding to, and which positions were newly initiated. This context makes it much easier to spot meaningful changes when the new filings drop.
Our superinvestors page shows each tracked manager's most recent portfolio alongside the quarter-over-quarter changes, so you can compare at a glance without having to manually cross-reference filings.
Have a research list ready
The most efficient use of 13F season is not to immediately act on new disclosures but to add interesting positions to a research queue. When you see that a manager you respect has initiated a new position, the right response is to put the company on your list to investigate — not to buy it immediately.
Having a structured research list ready before 13F season means you can quickly log new ideas as they emerge and work through them systematically in the following weeks.
The Most Important Things to Look For
When new 13F filings arrive, the data points that tend to generate the highest-quality research leads are:
New positions
A stock appearing in a manager's filing for the first time is generally the strongest signal. It means the manager has reviewed the opportunity, decided it meets their criteria, and allocated capital to it. A new position from a manager with high analytical standards and a long-term orientation is worth understanding.
The caveat: new positions in the most recent filing may actually have been initiated months earlier. A stock could have been purchased shortly after the previous quarter ended, meaning the manager has held it for up to five months before you see it in the filing.
Large additions to existing positions
When a manager meaningfully increases an existing position — adding 20%, 50%, or more to what they already owned — it suggests growing conviction. They reviewed the opportunity again after having held it for at least one quarter and decided to add more capital. This is a different and arguably stronger signal than the original initiation.
Complete exits from long-held positions
When a manager who has held a stock for several years suddenly removes it entirely from their portfolio, it is worth understanding why. Occasionally this reflects a fundamental change in the investment thesis. Sometimes it reflects the position hitting a target price. Either way, a long-term investor walking away from a position they held for years is informative.
Consensus — the same stock appearing across multiple managers
Some of the most useful research leads come not from any single manager's filing but from patterns across multiple managers. When three or four independent managers with different processes and philosophies all initiate or add to the same stock in the same quarter, it suggests that multiple separate analytical processes have arrived at the same conclusion. This convergence is worth investigating carefully.
We surface this in our consensus portfolio view, which aggregates holdings across all tracked superinvestors and highlights the stocks appearing most frequently.
How 13F Season Interacts With Earnings Season
There is a structural timing relationship between 13F season and earnings season that is worth understanding.
Earnings are typically reported in the weeks immediately following each quarter end — January and February for Q4, April and May for Q1, July and August for Q2, October and November for Q3. 13F filings arrive in the same window.
This means that when you are reviewing a manager's new position in a company, the company has often already reported earnings for the quarter in which the position was initiated. You have access to both the manager's decision to invest and the company's subsequent financial results, which can tell you whether the thesis appears to be playing out.
It also means that earnings news during 13F season can cause significant price moves in the same stocks appearing in new filings, creating occasional situations where you are looking at a new superinvestor position in a stock that has already moved 20–30% since quarter-end.
What 13F Season Cannot Tell You
The same limitations that apply to 13F data year-round apply with particular force during 13F season, when there is pressure to act quickly on new information.
The data is already old. Positions disclosed in a May filing reflect what was owned on March 31st. The manager may have added to the position, reduced it, or exited it entirely in the intervening weeks.
You only see the long book. Short positions, derivatives exposure, and cash levels are not in the filing. A manager who looks fully invested in equities based on their 13F may actually be running significant short positions or holding substantial cash elsewhere.
Filing volume creates noise. During 13F season, financial media covers hundreds of filings simultaneously. High-profile names generate disproportionate attention regardless of whether their moves are particularly meaningful. Resist the pressure to act on news flow and focus on the managers you have pre-selected as most relevant.
Following 13F Season on This Platform
Our superinvestors section is updated as new 13F filings are processed each quarter. For every tracked manager, you can see their complete current portfolio, the quarter-over-quarter changes, and a breakdown of new positions, additions, reductions, and complete exits.
We also surface the intersection of 13F data and insider trading data — showing you when company insiders are buying shares in the same stocks that superinvestors hold. This combination of independent signals, updated each quarter during 13F season, is one of the most useful research inputs available to the individual investor.
Summary
13F season is the quarterly period following each 13F filing deadline — February 14, May 15, August 14, and November 14 in 2026 — during which institutional investors disclose their equity holdings to the SEC.
For investors who track superinvestor portfolios, 13F season is among the most information-dense periods of the year. The most productive approach is to define in advance which managers you follow, focus on the highest-signal data points (new positions, large additions, complete exits, consensus holdings), and use the data to build a research queue rather than to trade immediately.
The 45-day lag means the data is never real-time. The managers worth following tend to be long-term investors for whom this limitation matters less than it would for shorter-horizon strategies. Used with appropriate context, the quarterly 13F cycle is one of the most reliable and accessible research frameworks available to individual investors.