Winthrop Advisory Group LLC MGNI — MAGNITE INC

Ownership history in Winthrop Advisory Group LLC  ·  7 quarters on record

AI Ownership Summary

Winthrop Advisory Group LLC reported MAGNITE INC (MGNI) in 7 quarterly 13F filings from 2024 Q3 through 2026 Q1. Peak portfolio weight reached 0.03% in 2025 Q2. The latest visible filing shows MGNI at 0.01% 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.

What this MGNI ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was Winthrop Advisory Group LLC's position in MAGNITE 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.

Freshest filing
Latest Reported Filing
2026 Q1

MGNI was reported at 0.01% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
0.03% in 2025 Q2

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

Time in book
Holding Window
2024 Q3 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.

MGNI stock page Winthrop Advisory Group LLC fund profile Winthrop Advisory Group LLC full holdings
How Winthrop Advisory Group LLC held MGNI — position size vs. price
% of Fund (quarterly)    MGNI price (quarter-end, indexed to 100)    SPY (indexed to 100)    QQQ (indexed to 100)
📋 Quarterly Holdings History 7 quarters  ▾
Quarter Action Sold % After 3M Timing Shares Change Chg % % of Fund Mkt Value Filed Price (Filed)
2026 Q1 UNCHANGED — — — 14,520 — 0% 0.01% $172K 2026-04-13 $12.09
2025 Q4 ADDED — — — 14,520 +440 +3.1% 0.02% $236K 2026-01-21 $14.29
2025 Q3 ADDED — — — 14,080 +80 +0.6% 0.03% $307K 2025-10-24 $19.94
2025 Q2 ADDED — — — 14,000 +600 +4.5% 0.03% $338K 2025-07-23 $22.55
2025 Q1 ADDED — — — 13,400 +200 +1.5% 0.02% $153K 2025-04-08 $9.00
2024 Q4 ADDED — — — 13,200 +300 +2.3% 0.03% $210K 2025-01-13 $15.53
2024 Q3 INITIATED — — — 12,900 — — 0.02% $179K 2024-10-31 $12.48

🏢 Other funds also holding MGNI

As of 2026 Q1 — sorted by position size

Kopion Asset Management, LLC 3Y 7.91% Maestria Partners LLC 5.91% P.A.W. CAPITAL CORP 3Y 7Y 5.5% 1492 Capital Management LLC 3Y 7Y 1.54% PERKINS CAPITAL MANAGEMENT INC 3Y 7Y 1.33% Penbrook Management LLC 3Y 7Y 1.01% STEINBERGANNA WEALTH MANAGEMENT 0.39% Bayforest Capital Ltd 0.18% Ledgewood Wealth Advisors, LLC 0.08% Murphy & Mullick Capital Management Corp 0.08%

FAQ About Winthrop Advisory Group LLC and MGNI

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

How long has Winthrop Advisory Group LLC reported owning MGNI?

Winthrop Advisory Group LLC reported MGNI across 7 quarterly 13F filings, from 2024 Q3 through 2026 Q1.

What was the largest reported MGNI position in Winthrop Advisory Group LLC's portfolio?

The largest reported portfolio weight for MGNI was 0.03% in 2025 Q2.

What is the latest reported MGNI position on this page?

The most recent filing on this page is 2026 Q1, when Winthrop Advisory Group LLC reported 14,520 shares, equal to 0.01% of portfolio, with an estimated market value of $172K.

What does the chart on this MGNI ownership page compare?

The chart compares Winthrop Advisory Group LLC's quarterly MGNI 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 Winthrop Advisory Group LLC time their MGNI position?

Based on 13F filing dates vs. subsequent MGNI price moves, Winthrop Advisory Group LLC correctly timed 2 out of 6 reported position changes (33%). The annualised alpha on MGNI relative to SPY over the holding period was +34.9%.

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