BLAIR WILLIAM & CO/IL BRK/B — BERKSHIRE HATHAWAY INC CL B COM

Ownership history in BLAIR WILLIAM & CO/IL  ·  104 quarters on record

AI Ownership Summary

BLAIR WILLIAM & CO/IL reported BERKSHIRE HATHAWAY INC CL B COM (BRK/B) in 104 quarterly 13F filings from 2023 Q4 through 2026 Q1. Peak portfolio weight reached 0.68% in 2026 Q1. The latest visible filing shows BRK/B at 0.68% of the fund.

This page tracks quarterly shares, estimated market value, portfolio weight, filing dates, and disclosure-aligned stock prices directly from SEC EDGAR 13F filings. Older history is available after unlock; the visible window still shows the most recent pattern.

What this BRK/B ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was BLAIR WILLIAM & CO/IL's position in BERKSHIRE HATHAWAY INC CL B COM, and how did that conviction change over time? You can read the holding window, peak weight, latest reported size, disclosure timing, and quarter-by-quarter changes without piecing the story together from raw SEC rows.

Freshest filing
Latest Reported Filing
2026 Q1

BRK/B was reported at 0.68% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
0.68% in 2026 Q1

Peak weight helps separate a token disclosure from a real conviction holding the fund genuinely cared about.

Time in book
Holding Window
2023 Q4 to 2026 Q1

Longer holding windows often tell a very different story from short-lived tactical trades or one-quarter experiments.

Decision context
Why It Matters
Position size beats headlines

Knowing that a fund owned a stock is useful. Knowing whether it was a 0.20% placeholder or a true high-conviction position is where the signal actually starts.

BRK/B stock page BLAIR WILLIAM & CO/IL fund profile BLAIR WILLIAM & CO/IL full holdings
How BLAIR WILLIAM & CO/IL held BRK/B — position size vs. price
% of Fund (quarterly)
📋 Quarterly Holdings History 10 quarters  ▾
Quarter Action Sold % After 3M Timing Shares Change Chg % % of Fund Mkt Value Filed Price (Filed)
2026 Q1 ADDED — — — 495,322 +48,260 +10.8% 0.68% $237.4M 2026-05-08 $469.32
2025 Q4 ADDED — — — 447,062 +1,828 +0.4% 0.60% $224.7M 2026-02-17 $503.41
2025 Q3 ADDED — — — 445,234 +2,637 +0.6% 0.60% $223.8M 2025-11-12 $502.40
2025 Q2 ADDED — — — 442,597 +21,843 +5.2% 0.60% $215.0M 2025-07-24 $480.60
2025 Q1 ADDED — — — 420,754 +1,635 +0.4% 0.68% $224.1M 2025-05-09 $513.74
2024 Q4 ADDED — — — 419,119 +11,262 +2.8% 0.55% $190.0M 2025-02-12 $471.73
2024 Q3 ADDED — — — 407,857 +1,553 +0.4% 0.55% $187.7M 2024-11-12 $466.29
2024 Q2 ADDED — — — 406,304 +10,605 +2.7% 0.51% $165.3M 2024-08-12 $430.39
2024 Q1 ADDED — — — 395,699 +15,215 +4.0% 0.52% $166.4M 2024-05-09 $408.82
2023 Q4 ADDED — — — 380,484 +24,857 +7.0% 0.46% $135.7M 2024-02-12 $397.71
94 older quarters hidden  —  Sign in free or upgrade to Premium to see full history

🏢 Other funds also holding BRK/B

As of 2026 Q1 — sorted by position size

TETRAD CORP 92.15% 1922 Investment Co LLC 3Y 7Y 84.86% CHECK CAPITAL MANAGEMENT INC/CA 3Y 7Y 52.8% Cook & Bynum Capital Management, LLC 3Y 7Y 42.7% Templeton & Phillips Capital Management, LLC 3Y 36.02% Aquamarine Zurich AG 3Y 34.57% Ardent Capital Management, Inc. 3Y 32.73% Asset Management Advisors, LLC 3Y 7Y 32.43% United American Securities Inc. (d/b/a UAS Asset Management) 3Y 7Y 31.97% Pacifica Capital Investments, LLC 3Y 7Y 30.79%

FAQ About BLAIR WILLIAM & CO/IL and BRK/B

These are the practical questions this page is built to answer before you even open the full history table.

How long has BLAIR WILLIAM & CO/IL reported owning BRK/B?

BLAIR WILLIAM & CO/IL reported BRK/B across 10 quarterly 13F filings, from 2023 Q4 through 2026 Q1.

What was the largest reported BRK/B position in BLAIR WILLIAM & CO/IL's portfolio?

The largest reported portfolio weight for BRK/B was 0.68% in 2026 Q1.

What is the latest reported BRK/B position on this page?

The most recent filing on this page is 2026 Q1, when BLAIR WILLIAM & CO/IL reported 495,322 shares, equal to 0.68% of portfolio, with an estimated market value of $237.4M.

What does the chart on this BRK/B ownership page compare?

The chart compares BLAIR WILLIAM & CO/IL's quarterly BRK/B portfolio weight with the stock's indexed share price, so you can see whether the fund was building, trimming, or holding the position as price moved.

How well did BLAIR WILLIAM & CO/IL time their BRK/B position?

Based on 13F filing dates vs. subsequent BRK/B price moves, BLAIR WILLIAM & CO/IL correctly timed 56 out of 103 reported position changes (54%). The annualised alpha on BRK/B relative to SPY over the holding period was +1.2%.

← Back to BLAIR WILLIAM & CO/IL Holdings