WINMILL & CO. INC reported INTERACTIVE BROKERS GROUP, INC. (IBKR) in 9 quarterly 13F filings from 2023 Q4 through 2025 Q4. Peak portfolio weight reached 5.61% in 2025 Q4. The latest visible filing shows IBKR at 5.61% 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.
This page is designed to answer the real investor question behind a 13F filing: how meaningful was WINMILL & CO. INC's position in INTERACTIVE BROKERS GROUP, INC., 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.
IBKR was reported at 5.61% of portfolio in the most recent visible filing.
Peak weight helps separate a token disclosure from a real conviction holding the fund genuinely cared about.
Longer holding windows often tell a very different story from short-lived tactical trades or one-quarter experiments.
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.
These are the practical questions this page is built to answer before you even open the full history table.
WINMILL & CO. INC reported IBKR across 9 quarterly 13F filings, from 2023 Q4 through 2025 Q4.
The largest reported portfolio weight for IBKR was 5.61% in 2025 Q4.
The most recent filing on this page is 2025 Q4, when WINMILL & CO. INC reported 327,200 shares, equal to 5.61% of portfolio, with an estimated market value of $21.0M.
The chart compares WINMILL & CO. INC's quarterly IBKR 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.