WINMILL & CO. INC BRK/B — D Berkshire Hathaway Inc.- Cl B Common Stock

Ownership history in WINMILL & CO. INC  ·  30 quarters on record

AI Ownership Summary

WINMILL & CO. INC reported D Berkshire Hathaway Inc.- Cl B Common Stock (BRK/B) in 30 quarterly 13F filings from 2023 Q4 through 2026 Q1. Peak portfolio weight reached 0.83% in 2025 Q1. The latest visible filing shows BRK/B at 0.35% 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 WINMILL & CO. INC's position in D Berkshire Hathaway Inc.- Cl B Common Stock, 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 0.35% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
0.83% in 2025 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 WINMILL & CO. INC fund profile WINMILL & CO. INC full holdings
How WINMILL & CO. INC 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 REDUCED — — — 2,500 -500 -16.7% 0.35% $1.2M 2026-05-14 $469.32
2025 Q4 REDUCED — — — 3,000 -2,100 -41.2% 0.40% $1.5M 2026-02-13 $497.55
2025 Q3 UNCHANGED — — — 5,100 — 0% 0.62% $2.6M 2025-11-13 $513.11
2025 Q2 UNCHANGED — — — 5,100 — 0% 0.69% $2.5M 2025-08-01 $472.84
2025 Q1 UNCHANGED — — — 5,100 — 0% 0.83% $2.7M 2025-05-14 $503.40
2024 Q4 UNCHANGED — — — 5,100 — 0% 0.75% $2.3M 2025-02-13 $480.49
2024 Q3 UNCHANGED — — — 5,100 — 0% 0.79% $2.3M 2024-11-13 $468.10
2024 Q2 REDUCED — — — 5,100 -1,010 -16.5% 0.71% $2.1M 2024-08-13 $432.41
2024 Q1 UNCHANGED — — — 6,110 — 0% 0.73% $2.6M 2024-05-14 $410.24
2023 Q4 UNCHANGED — — — 6,110 — 0% 0.70% $2.2M 2024-02-13 $394.80
20 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 WINMILL & CO. INC 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 WINMILL & CO. INC reported owning BRK/B?

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

What was the largest reported BRK/B position in WINMILL & CO. INC's portfolio?

The largest reported portfolio weight for BRK/B was 0.83% in 2025 Q1.

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

The most recent filing on this page is 2026 Q1, when WINMILL & CO. INC reported 2,500 shares, equal to 0.35% of portfolio, with an estimated market value of $1.2M.

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

The chart compares WINMILL & CO. INC'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 WINMILL & CO. INC time their BRK/B position?

Based on 13F filing dates vs. subsequent BRK/B price moves, WINMILL & CO. INC correctly timed 6 out of 8 reported position changes (75%). The annualised alpha on BRK/B relative to SPY over the holding period was +0.2%.

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