Comparable stake leader
BlackRock, Inc.
SEC ownership of MONOLITHIC POWER SYSTEMS INC
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001280452.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
01 Jun 2026
- Public ticker
- MPWR on Nasdaq
- Parsed ownership sources
- 13F, 13D/G, and 3/4/5
- Largest SEC-reported holder
- BlackRock, Inc.
- Latest 13D/G holder
- BlackRock, Inc.
- Latest parsed ownership date
- 01 Jun 2026
- Issuer CIK
- 0001280452
- Issuer location
- West Palm Beach, FL
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of MONOLITHIC POWER SYSTEMS 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
BlackRock, Inc.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
01 Jun 2026
13F
13D/G
3/4/5
Lead comparable stake: 10%
13D/G row: BlackRock, Inc.
Showing 1-8 of 50 holder rows.
Quick read
BlackRock, Inc. leads the comparable SEC ownership view at 10%.
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 BlackRock, Inc.'s linked filing trail.
Comparable ownership
Top 5
BlackRock, Inc.
10%
FMR LLC
8.3%
VANGUARD CAPITAL MANAGEMENT LLC
7.2%
VANGUARD PORTFOLIO MANAGEMENT LLC
5.1%
Mr. Michael R. Hsing
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 |
|---|---|---|---|---|---|
| BlackRock, Inc. |
13F
13D/G
Company
|
10%
from 13D/G
|
$6,639,332,032
6,072,467 shares
|
— | 31 Mar 2026 |
| FMR LLC |
13F
13D/G
Company
|
8.3%
from 13D/G
|
$4,811,648,189
4,400,831 shares
|
— | 31 Mar 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13D/G
13F
Vanguard Capital Management · Company
|
7.2%
|
$3,894,366,547
3,561,866 shares
|
$0 | 31 Mar 2026 |
| VANGUARD PORTFOLIO MANAGEMENT LLC |
13D/G
13F
Vanguard Portfolio Management · Company
|
5.1%
|
$2,765,003,682
2,528,928 shares
|
$0 | 31 Mar 2026 |
| Mr. Michael R. Hsing |
3/4/5
CEO, Director
|
2%
|
$1,450,054,273
994,128 shares
|
-$331,209,548 | 18 May 2026 |
| Mr. Maurice Sciammas |
3/4/5
EVP, WW Sales & Marketing
|
0.51%
|
$273,312,475
249,502 shares
|
-$81,059,330 | 01 Jun 2026 |
| Mr. Deming Xiao |
3/4/5
EVP, Global Operations
|
0.47%
|
$369,281,405
230,750 shares
|
-$107,626,150 | 06 May 2026 |
| Saria Tseng |
3/4/5
EVP & General Counsel
|
0.3%
|
$246,263,950
145,218 shares
|
-$164,165,495 | 27 May 2026 |
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: -$763,781,231.
Buys
$0
Insiders: 0
Sells
$763,781,231
Insiders: 12
Net
-$763,781,231
Shares: -683,021
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 683,021
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 153,099 | $0 | $220,228,738 | -$220,228,738 |
| 3-6 | 0 | 253,473 | $0 | $295,322,129 | -$295,322,129 |
| 6-9 | 0 | 199,426 | $0 | $187,003,811 | -$187,003,811 |
| 9-12 | 0 | 77,023 | $0 | $61,226,553 | -$61,226,553 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-13 of 13 reporting-owner rows connected to MONOLITHIC POWER SYSTEMS INC. Open a relationship link for the CIK-to-CIK filing trail.
Rows
13
Largest Forms 3/4/5 holder
Mr. Michael R. Hsing
Net 12M change
-$763,781,231
Latest report
01 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Mr. Michael R. Hsing | CEO, Director | $1,450,054,273 | -$331,209,548 | -19% | Mixed | 18 May 2026 |
| Mr. Deming Xiao | EVP, Global Operations | $369,281,405 | -$107,626,150 | -23% | Mixed | 06 May 2026 |
| Mr. Maurice Sciammas | EVP, WW Sales & Marketing | $273,312,475 | -$81,059,330 | -23% | Mixed | 01 Jun 2026 |
| Saria Tseng | EVP & General Counsel | $246,263,950 | -$164,165,495 | -40% | Mixed | 27 May 2026 |
| Theodore Blegen | EVP and CFO | $106,631,372 | -$49,384,778 | -32% | Mixed | 06 Feb 2026 |
| Mr. Victor K. Lee | Director | $33,644,712 | -$1,995,099 | -5.6% | Filing P/S | 09 Feb 2026 |
| Mr. James C. Moyer | Director | $15,372,900 | Mixed | 29 Aug 2024 | ||
| Mr. Robert W. Dean II | Interim CFO | $9,767,180 | -$42,543 | -0.43% | Mixed | 26 May 2026 |
| Mr. Eugen J. Elmiger | Director | $8,643,956 | -$22,406,323 | -72% | Filing P/S | 06 May 2026 |
| Mr. Jeff Zhou | Director | $6,384,000 | -$3,924,673 | -38% | Filing P/S | 26 May 2026 |
| Ms. Eileen Wynne | Director | $1,593,758 | -$530,198 | -25% | Filing P/S | 06 May 2026 |
| Ms. Carintia Martinez | Director | $967,086 | -$1,260,000 | -57% | Mixed | 03 Feb 2026 |
| Mr. Herbert Chang | Director | $557,411 | -$177,094 | -24% | Mixed | 03 Feb 2026 |
Recent insider transactions for MONOLITHIC POWER SYSTEMS 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -2.48% | $46,018 | $1533.95 | -30 | 1,179 | 01 Jun 2026 | Clement Sciammas Trust |
| Mr. Maurice Sciammas | MPWR | Common Stock | Gift | -49.7% | -12,472 | 12,625 | 29 May 2026 | Various Sciammas GRATs | ||
| Saria Tseng | MPWR | Common Stock | Sale | -4.98% | $12,860,500 | $1700.00 | -7,565 | 144,218 | 27 May 2026 | Direct |
| Mr. Robert W. Dean II | MPWR | Common Stock | Sale | -0.37% | $36,290 | $1649.56 | -22 | 5,878 | 26 May 2026 | Direct |
| Mr. Jeff Zhou | MPWR | Common Stock | Sale | -11.3% | $816,480 | $1680.00 | -486 | 3,800 | 26 May 2026 | Direct |
| Saria Tseng | MPWR | Common Stock | Sale | -3.19% | $7,932,150 | $1586.43 | -5,000 | 151,783 | 22 May 2026 | Direct |
| Saria Tseng | MPWR | Common Stock | Gift | -0.13% | -200 | 156,783 | 22 May 2026 | Direct | ||
| Mr. Michael R. Hsing | MPWR | Common Stock | Sale | -4.5% | $59,310,169 | $1482.75 | -40,000 | 848,263 | 18 May 2026 | Direct |
| Mr. Robert W. Dean II | MPWR | Common Stock | Sale | -0.07% | $6,253 | $1563.28 | -4 | 5,900 | 18 May 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -6.72% | $18,736,850 | $1561.40 | -12,000 | 166,644 | 15 May 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Gift | 3.16% | 1,563 | 51,023 | 13 May 2026 | Sciammas Family Trust | ||
| Mr. Maurice Sciammas | MPWR | Common Stock | Gift | -5.86% | -1,563 | 25,097 | 13 May 2026 | Various Sciammas GRATs | ||
| Mr. Robert W. Dean II | MPWR | Common Stock | Other | -26.8% | -2,156 | 5,904 | 13 May 2026 | Direct | ||
| Mr. Eugen J. Elmiger | MPWR | Common Stock | Sale | -69% | $19,019,482 | $1584.96 | -12,000 | 5,402 | 06 May 2026 | Direct |
| Mr. Deming Xiao | MPWR | Common Stock | Sale | -12.7% | $49,636,560 | $1654.55 | -30,000 | 205,959 | 06 May 2026 | Direct |
| Ms. Eileen Wynne | MPWR | Common Stock | Sale | -25% | $530,198 | $1582.68 | -335 | 1,007 | 06 May 2026 | Direct |
| Mr. Jeff Zhou | MPWR | Common Stock | Sale | -10.4% | $825,000 | $1650.00 | -500 | 4,286 | 06 May 2026 | Direct |
| Mr. Jeff Zhou | MPWR | Common Stock | Sale | -17.5% | $1,609,283 | $1587.06 | -1,014 | 4,786 | 05 May 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -29.2% | $601,848 | $1583.81 | -380 | 919 | 05 May 2026 | Rosalind Sciammas Brokerage Account |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -2.42% | $47,662 | $1588.73 | -30 | 1,209 | 04 May 2026 | Clement Sciammas Trust |
| Saria Tseng | MPWR | Common Stock | Sale | -5.4% | $11,698,654 | $1305.22 | -8,963 | 156,983 | 08 Apr 2026 | Direct |
| Saria Tseng | MPWR | Common Stock | Sale | -4.4% | $8,918,434 | $1167.95 | -7,636 | 165,946 | 06 Apr 2026 | Direct |
| Saria Tseng | MPWR | Common Stock | Sale | -0.8% | $1,586,924 | $1133.52 | -1,400 | 173,582 | 01 Apr 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -2.36% | $33,493 | $1116.44 | -30 | 1,239 | 01 Apr 2026 | Clement Sciammas Trust |
| Saria Tseng | MPWR | Common Stock | Sale | -12.8% | $25,943,638 | $1010.50 | -25,674 | 174,982 | 30 Mar 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -2.31% | $32,852 | $1095.07 | -30 | 1,269 | 20 Mar 2026 | Clement Sciammas Trust |
| Mr. Michael R. Hsing | MPWR | Common Stock | Sale | -3.58% | $38,670,257 | $1171.83 | -33,000 | 888,234 | 12 Feb 2026 | Direct |
| Mr. Michael R. Hsing | MPWR | Common Stock | Sale | -3.46% | $39,234,212 | $1188.92 | -33,000 | 921,234 | 11 Feb 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -13.3% | $235,995 | $1179.98 | -200 | 1,299 | 11 Feb 2026 | Clement Sciammas Trust |
| Mr. Michael R. Hsing | MPWR | Common Stock | Sale | -3.44% | $38,837,435 | $1142.28 | -34,000 | 954,234 | 10 Feb 2026 | Direct |
| Mr. Victor K. Lee | MPWR | Common Stock | Sale | -1.42% | $484,864 | $1212.16 | -400 | 27,756 | 09 Feb 2026 | Direct |
| Mr. Deming Xiao | MPWR | Common Stock | Sale | -8.84% | $26,790,370 | $1171.16 | -22,875 | 235,932 | 06 Feb 2026 | Direct |
| Saria Tseng | MPWR | Common Stock | Sale | -10.2% | $26,790,370 | $1171.16 | -22,875 | 200,626 | 06 Feb 2026 | Direct |
| Mr. Maurice Sciammas | MPWR | Common Stock | Sale | -11.4% | $26,790,370 | $1171.16 | -22,875 | 178,625 | 06 Feb 2026 | Direct |
| Theodore Blegen | MPWR | Common Stock | Sale | -20.9% | $25,443,531 | $1171.16 | -21,725 | 82,353 | 06 Feb 2026 | Direct |
| Mr. Michael R. Hsing | MPWR | Common Stock | Sale | -5.27% | $64,323,824 | $1171.16 | -54,923 | 988,234 | 06 Feb 2026 | Direct |
| Ms. Eileen Wynne | MPWR | Common Stock | Award | 16.4% | 189 | 1,342 | 03 Feb 2026 | Direct | ||
| Mr. Jeff Zhou | MPWR | Common Stock | Award | 3.37% | 189 | 5,800 | 03 Feb 2026 | Direct | ||
| Mr. Eugen J. Elmiger | MPWR | Common Stock | Award | 1.1% | 189 | 17,402 | 03 Feb 2026 | Direct | ||
| Mr. Victor K. Lee | MPWR | Common Stock | Award | 0.68% | 189 | 28,156 | 03 Feb 2026 | Direct | ||
| Ms. Carintia Martinez | MPWR | Common Stock | Award | 21.5% | 189 | 1,067 | 03 Feb 2026 | Direct | ||
| Mr. Deming Xiao | MPWR | Common Stock | Award | 28.4% | 57,170 | 258,807 | 03 Feb 2026 | Direct | ||
| Theodore Blegen | MPWR | Common Stock | Award | 59.3% | 38,745 | 104,078 | 03 Feb 2026 | Direct | ||
| Saria Tseng | MPWR | Common Stock | Award | 34.4% | 57,170 | 223,501 | 03 Feb 2026 | Direct | ||
| Mr. Michael R. Hsing | MPWR | Common Stock | Award | 15.1% | 136,825 | 1,043,157 | 03 Feb 2026 | Direct | ||
| Mr. Maurice Sciammas | MPWR | Common Stock | Award | 39.6% | 57,170 | 201,500 | 03 Feb 2026 | Direct | ||
| Mr. Herbert Chang | MPWR | Common Stock | Award | 44.4% | 189 | 615 | 03 Feb 2026 | Direct | ||
| Theodore Blegen | MPWR | Common Stock | Sale | -4.39% | $3,389,266 | $1129.76 | -3,000 | 65,333 | 02 Feb 2026 | Direct |
| Mr. Victor K. Lee | MPWR | Common Stock | Sale | -2.1% | $558,516 | $930.86 | -600 | 27,967 | 02 Jan 2026 | Direct |
| Theodore Blegen | MPWR | Common Stock | Sale | -4.21% | $2,821,399 | $940.47 | -3,000 | 68,332 | 02 Jan 2026 | Direct |
* marks a reported price that did not pass the local price check.