SEC ownership of MediaAlpha, Inc.

Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001818383.

Comparable stake leader

WHITE MOUNTAINS INSURANCE GROUP LTD

Disclosed value leader

WHITE MOUNTAINS INSURANCE GROUP LTD

Comparable rows

50/50

Latest evidence

21 Jul 2026

Top shareholders Insider holders Latest transactions
Public ticker
MAX on NYSE
Parsed ownership sources
3/4/5, 13D/G, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
Largest SEC-reported holder
WHITE MOUNTAINS INSURANCE GROUP LTD
Ranking: Comparable ownership first, then disclosed value
Ownership snapshot CIK-linked ownership evidence from parsed SEC filings. 3 signals
Comparable ownership rows
50 of 50
Meaning: Rows with safely comparable ownership %
Latest 13D/G holder
WHITE MOUNTAINS INSURANCE GROUP LTD
Source: Latest parsed Schedule 13D/G stake
Latest parsed ownership date
21 Jul 2026
Freshness: Most recent filing date in this holder set
Issuer Names, identifiers, and filing context for this profile. 2 identity fields
Issuer CIK
0001818383
Issuer location
Los Angeles, CA

Ownership snapshot

Top shareholders of MediaAlpha, Inc. (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.

Comparable stake leader
WHITE MOUNTAINS INSURANCE...
Disclosed value leader
WHITE MOUNTAINS INSURANCE...
Comparable rows
50/50
Latest evidence
21 Jul 2026
3/4/5 13D/G 13F Lead comparable stake: 33% 13D/G row: WHITE MOUNTAINS INSURANCE GROUP LTD Showing 1-8 of 50 holder rows.

Quick read

WHITE MOUNTAINS INSURANCE GROUP LTD leads the comparable SEC ownership view at 33%.

50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.

Open SEC evidence Opens WHITE MOUNTAINS INSURANCE GROUP LTD's linked filing trail.
Comparable ownership Top 5
WHITE MOUNTAINS INSURANCE GROUP LTD 33%
Eugene Nonko 11%
Divisadero Street Capital Managem... 5.8%
VANGUARD GROUP INC 4.6%
BlackRock, Inc. 4.2%

Ownership % is shown only when SEC disclosures are safely comparable across share classes.

Detailed SEC evidence table Showing 1-8 of 50 holder rows
Holder Evidence Ownership % Position 12M Net Δ As of
WHITE MOUNTAINS INSURANCE GROUP LTD
3/4/5 13D/G 13F
10%+ Owner · Company
3/4/5 13D/G 13F
33%
from 13D/G
$339,275,666
17,856,614 shares
 — 07 May 2024
Eugene Nonko
13D/G 3/4/5
Director
13D/G 3/4/5
11%
$50,433,626
5,996,864 shares
 $0 26 Feb 2025
Divisadero Street Capital Management, LP
13D/G 13F
Company
13D/G 13F
5.8%
$39,331,379
3,128,988 shares
 $0 21 Jul 2026
VANGUARD GROUP INC
13D/G
The Vanguard Group
13D/G
4.6%
$29,595,067
2,600,621 shares
 -$3,558,606 30 Sep 2025
BlackRock, Inc.
13F 13D/G
Company
13F 13D/G
4.2%
from 13D/G
$42,641,927
3,392,357 shares
 — 30 Jun 2026
VRABECK KATHY P
3/4/5
Director
3/4/5
0.28%
$1,398,785
150,407 shares
 — 05 May 2026
Venmal (raji) Arasu
3/4/5
Director
3/4/5
0.22%
$1,110,485
119,407 shares
 — 05 May 2026
Lara Sweet
3/4/5
Director
3/4/5
0.18%
$829,705
98,657 shares
 — 14 May 2025
How to read this table

Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

Forms 3/4/5 flow

Insider trading overview

Net insider flow leans to selling over the last 12 months. Net value: -$28,771,223.

Buys
$0
Insiders: 0
Sells
$28,771,223
Insiders: 5
Net
-$28,771,223
Shares: -2,452,982
Window
Last 12 months
4 rolling buckets
Buy value Sell value
Shares: 0 Shares: 2,452,982
Window (months) Buy shares Sell shares Buy value Sell value Net value
0-3 0 917,485 $0 $12,097,811 -$12,097,811
3-6 0 738,997 $0 $7,254,721 -$7,254,721
6-9 0 776,400 $0 $9,171,022 -$9,171,022
9-12 0 20,100 $0 $247,668 -$247,668

Reporting owners

Insider holders from Forms 3/4/5

Showing 1-20 of 26 reporting-owner rows connected to MediaAlpha, Inc.. Open a relationship link for the CIK-to-CIK filing trail.

Rows
26
Largest Forms 3/4/5 holder
WHITE MOUNTAINS INSURANCE GROUP LTD
Net 12M change
-$28,771,223
Latest report
10 Aug 2026
Name Relationship Holdings Value Past Year Net Change Change % Valuation Report Date
WHITE MOUNTAINS INSURANCE GROUP LTD 10%+ Owner $339,275,666 Filing P/S 07 May 2024
WM Birkdale, Ltd. 10%+ Owner $153,342,381 Mixed 22 Dec 2022
INSIGNIA CAPITAL PARTNERS GP, L.L.C. 10%+ Owner $61,462,986 Mixed 09 May 2024
WM Hinson (Bermuda) Ltd. 10%+ Owner $56,564,761 Mixed 30 Jun 2023
Steven Yi CHIEF EXECUTIVE OFFICER, PRESIDENT, AND CO-FOUNDER, Director $31,112,713 -$12,968,607 -29% Mixed 03 Aug 2026
Eugene Nonko Director $24,337,986 -$13,945,015 -36% Mixed 10 Aug 2026
Patrick Ryan Thompson Chief Financial Officer and Treasurer $10,644,982 Mixed 15 May 2026
Kuanling Amy Yeh Chief Technology Officer $7,728,090 -$793,130 -9.3% Filing P/S 16 Jul 2026
Jeffrey B. Coyne General Counsel And Secretary $5,114,292 -$142,789 -2.7% Mixed 15 May 2026
Keith Cramer Chief Revenue Officer $4,482,543 -$921,682 -17% Mixed 15 Jul 2026
Ambrose Wang Co Founder $2,478,768 Mixed 30 Jul 2021
Brian Mikalis Senior Vice President, Demand Partnerships $2,139,216 Mixed 30 Oct 2021
Jeff Sweetser Vice President, Supply Partnerships $1,765,299 Mixed 30 Oct 2021
VRABECK KATHY P Director $1,398,785 Mixed 05 May 2026
Robert Perine Vice President, Product $1,317,798 Mixed 30 Oct 2021
Serge Topjian Vice President, Media $1,139,054 Mixed 30 Oct 2021
Venmal (raji) Arasu Director $1,110,485 Mixed 05 May 2026
Lara Sweet Director $829,705 Mixed 14 May 2025
Cort Allan Carlson VP, Corporate Controller and Interim Principal Financial and Accounting Officer $530,346 Mixed 15 Nov 2021
Bradley William Hunt Director $429,660 Mixed 05 May 2026

Recent insider transactions for MediaAlpha, Inc.

Showing up to 300 recent insider transactions from the last 12 months.

Insider Symbol Class Transaction % SEC-reported value SEC-reported price Shares Shares owned Date Ownership
Eugene Nonko MAX Class A Common Stock Sale -0.83% $104,866 $12.78 -8,205 984,164 12 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.39% $42,289 $12.89 -3,282 842,400 12 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.82% $108,610 $13.24 -8,205 992,369 11 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.39% $43,835 $13.36 -3,282 845,682 11 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.81% $111,330 $13.57 -8,205 1,000,574 10 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.39% $43,666 $13.30 -3,282 848,964 10 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.77% $95,520 $12.28 -7,778 1,008,779 05 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.31% $32,974 $12.36 -2,667 852,246 05 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.76% $96,819 $12.45 -7,778 1,016,557 04 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.31% $33,346 $12.50 -2,667 854,913 04 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.79% $102,423 $12.48 -8,205 1,024,335 03 Aug 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.38% $41,157 $12.54 -3,282 857,580 03 Aug 2026 Direct
Steven Yi MAX Class A Common Stock Sale -2.93% $909,994 $12.64 -72,000 2,387,690 03 Aug 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.91% $133,780 $14.05 -9,524 1,032,540 29 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.57% $69,571 $14.05 -4,952 860,862 29 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -1.03% $149,375 $13.78 -10,843 1,042,064 28 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.76% $91,776 $13.86 -6,622 865,814 28 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.77% $108,933 $13.28 -8,205 1,052,907 27 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.37% $43,572 $13.28 -3,282 872,436 27 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.89% $130,600 $13.71 -9,524 1,061,112 22 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.56% $68,399 $13.81 -4,952 875,718 22 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.88% $136,475 $14.33 -9,524 1,070,636 21 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.56% $70,971 $14.33 -4,952 880,670 21 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.87% $131,658 $13.82 -9,524 1,080,160 20 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.56% $68,685 $13.87 -4,952 885,622 20 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -0.5% $175,095 $14.20 -12,333 2,459,690 17 Jul 2026 Direct
Kuanling Amy Yeh MAX Class A Common Stock Sale -0.54% $41,850 $13.95 -3,000 553,985 17 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -3.23% $1,186,564 $14.39 -82,457 2,472,023 16 Jul 2026 Direct
Kuanling Amy Yeh MAX Class A Common Stock Sale -1.76% $145,080 $14.51 -10,000 556,985 16 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.87% $134,675 $14.14 -9,524 1,089,684 15 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.55% $69,456 $14.03 -4,952 890,574 15 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -4.28% $1,619,118 $14.17 -114,292 2,554,480 15 Jul 2026 Direct
Keith Cramer MAX Class A Common Stock Sale -4.63% $184,495 $14.19 -13,000 267,528 15 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.86% $132,410 $13.90 -9,524 1,099,208 14 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.55% $68,599 $13.85 -4,952 895,526 14 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -1.39% $530,004 $14.06 -37,701 2,668,772 14 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.97% $149,208 $13.76 -10,843 1,108,732 13 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.73% $91,427 $13.81 -6,622 900,478 13 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -0.35% $133,397 $14.05 -9,496 2,706,473 13 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.73% $111,664 $13.61 -8,205 1,119,575 08 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.36% $45,227 $13.78 -3,282 907,100 08 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -0.97% $372,452 $14.07 -26,467 2,715,969 07 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.84% $133,898 $14.06 -9,524 1,127,780 07 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.54% $69,744 $14.08 -4,952 910,382 07 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -0.63% $241,782 $14.01 -17,254 2,742,436 06 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -2.18% $351,447 $13.86 -25,352 1,137,304 06 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -2.66% $347,681 $13.91 -24,992 915,334 06 Jul 2026 Direct
Eugene Nonko MAX Class A Common Stock Sale -0.77% $115,975 $12.80 -9,059 1,162,656 01 Jul 2026 By O.N.E. Holdings,LLC
Eugene Nonko MAX Class A Common Stock Sale -0.48% $57,634 $12.77 -4,512 940,326 01 Jul 2026 Direct
Steven Yi MAX Class A Common Stock Sale -3.36% $1,238,669 $12.90 -96,000 2,759,690 01 Jul 2026 Direct
* marks a reported price that did not pass the local price check.
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