Comparable stake leader
WHITE MOUNTAINS INSURANCE GROUP LTD
SEC ownership of MediaAlpha, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001818383.
Disclosed value leader
WHITE MOUNTAINS INSURANCE GROUP LTD
Comparable rows
49/50
Latest evidence
21 Jul 2026
- 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
- Comparable ownership rows
-
49 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 CIK
- 0001818383
- Issuer location
- Los Angeles, CA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
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
49/50
Latest evidence
21 Jul 2026
3/4/5
13D/G
13F
Lead comparable stake: 33%
1 rows are not safely comparable across share classes.
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%.
49 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
10%+ Owner
|
33%
from 13D/G
|
$339,275,666
17,856,614 shares
|
— | 07 May 2024 |
| Eugene Nonko |
13D/G
3/4/5
Director
|
11%
|
$50,433,626
5,996,864 shares
|
$0 | 26 Feb 2025 |
| Divisadero Street Capital Management, LP |
13D/G
|
5.8%
|
$39,331,379
3,128,988 shares
|
$0 | 21 Jul 2026 |
| VANGUARD GROUP INC |
13D/G
The Vanguard Group
|
4.6%
|
$29,595,067
2,600,621 shares
|
-$3,558,606 | 30 Sep 2025 |
| BlackRock, Inc. |
13F
13D/G
Company
|
4.2%
from 13D/G
|
$42,641,927
3,392,357 shares
|
— | 30 Jun 2026 |
| VRABECK KATHY P |
3/4/5
Director
|
0.28%
|
$1,398,785
150,407 shares
|
+$297,575 | 05 May 2026 |
| Venmal (raji) Arasu |
3/4/5
Director
|
0.22%
|
$1,110,485
119,407 shares
|
— | 05 May 2026 |
| Lara Sweet |
3/4/5
Director
|
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: -$28,377,799.
Buys
$0
Insiders: 0
Sells
$28,377,799
Insiders: 5
Net
-$28,377,799
Shares: -2,424,521
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 2,424,521
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 883,024 | $0 | $11,643,216 | -$11,643,216 |
| 3-6 | 0 | 752,997 | $0 | $7,354,957 | -$7,354,957 |
| 6-9 | 0 | 782,500 | $0 | $9,318,454 | -$9,318,454 |
| 9-12 | 0 | 6,000 | $0 | $61,172 | -$61,172 |
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
-$28,322,485
Latest report
03 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 | $23,830,616 | -$13,490,420 | -36% | Mixed | 03 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 | -$854,302 | -10% | 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 | -$1,163,942 | -21% | 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 | +$297,575 | +27% | 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 | -0.77% | $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 |
| Eugene Nonko | MAX | Class A Common Stock | Sale | -0.66% | $96,750 | $12.44 | -7,778 | 1,171,715 | 30 Jun 2026 | By O.N.E. Holdings,LLC |
| Eugene Nonko | MAX | Class A Common Stock | Sale | -0.28% | $33,134 | $12.42 | -2,667 | 944,838 | 30 Jun 2026 | Direct |
| Eugene Nonko | MAX | Class A Common Stock | Sale | -0.66% | $92,813 | $11.93 | -7,778 | 1,179,493 | 29 Jun 2026 | By O.N.E. Holdings,LLC |
| Eugene Nonko | MAX | Class A Common Stock | Sale | -0.28% | $31,509 | $11.81 | -2,667 | 947,505 | 29 Jun 2026 | Direct |
| Kuanling Amy Yeh | MAX | Class A Common Stock | Sale | -0.53% | $33,480 | $11.16 | -3,000 | 566,985 | 26 Jun 2026 | Direct |
| Eugene Nonko | MAX | Class A Common Stock | Sale | -0.56% | $69,771 | $10.47 | -6,667 | 1,187,271 | 24 Jun 2026 | By O.N.E. Holdings,LLC |
* marks a reported price that did not pass the local price check.