MPWR SEC Filing News — Monolithic Power Systems, Inc.

Latest SEC filings for Monolithic Power Systems, Inc. (MPWR) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). All data sourced directly from SEC EDGAR — last updated 2026-09-02.

Monolithic Power Systems, Inc. provides semiconductor-based power electronics solutions in China, Taiwan, South Korea, Southeast Asia, Europe, the United States, Japan, and internationally. The company offers direct current (DC) to DC solutions to convert and control voltages within a range of electronic systems, such as cloud-based and on-premises CPU servers and workstations, AI systems, memory, storage solutions, notebooks, infotainment, power sources, home appliances, network infrastructure,…
Sector: Technology Industry: Semiconductors Market Cap: $58.5B CIK: 1280452
20
Total Filings
0
Bullish Signals
10
Bearish Signals
12
Insider Transactions
2
Material Events (8-K)
1
Periodic Reports
Insider activity for MPWR has skewed bearish recently. Of the 20 filings tracked, 10 carry bearish signals (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.
MPWR Filing Activity Snapshot 2026-06-03 — 2026-09-02
Insider Transactions (Form 4)
0 buys vs 9 sells
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Transaction
$40.49M
MAURICE SCIAMMAS · 2026-07-15
15,000 shares · Form 144
Form 144 Notices
5
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 12 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 12 filings in this group are Form 4s for Monolithic Power Systems, Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 12 insider filings shown, the breakdown is 9 open-market sale, 2 gift and 1 compensation award. 9 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Open-market sale ×9
The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.
Gift ×2
Shares were transferred as a gift, typically for estate or charitable planning. No sale into the market took place.
Compensation award ×1
Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.
Form 4 Gift Tax / Compensation Filing 2026-09-02

MPWR insider Form 4 filed for equity award, exercise, or tax withholding

Tseng Saria (EVP & General Counsel) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were transferred as a gift, typically for estate or charitable planning. No sale into the market took place.

Transactions reported on this filing
Code Nature Shares Price Value
G Gift 2,000 — —
G Gift 2,000 — —
Filing: Form 4 (Insider Transaction) Insider: Tseng Saria (EVP & General Counsel) Shares: 4,000
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-26

MPWR insider DEAN ROBERT W II (Interim CFO) sold 32 shares (~$41.5K)

DEAN ROBERT W II, listed as Interim CFO at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 32 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 32 $1,297.72 $41.5K
J Other transaction 5 — —
Filing: Form 4 (Insider Transaction) Insider: DEAN ROBERT W II (Interim CFO) Shares: 32 Est. Value: $41.5K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-25

MPWR insider CHANG KUO WEI HERBERT (Director) sold 50 shares (~$64.1K)

CHANG KUO WEI HERBERT, listed as Director at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 50 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 50 $1,281.57 $64.1K
Filing: Form 4 (Insider Transaction) Insider: CHANG KUO WEI HERBERT (Director) Shares: 50 Est. Value: $64.1K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-19

MPWR insider DEAN ROBERT W II (Interim CFO) sold 6 shares (~$8.5K)

DEAN ROBERT W II, listed as Interim CFO at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 6 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 6 $1,413.64 $8.5K
Filing: Form 4 (Insider Transaction) Insider: DEAN ROBERT W II (Interim CFO) Shares: 6 Est. Value: $8.5K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-13

MPWR insider CHANG KUO WEI HERBERT (Director) sold 50 shares (~$71.0K)

CHANG KUO WEI HERBERT, listed as Director at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 50 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 50 $1,420.00 $71.0K
Filing: Form 4 (Insider Transaction) Insider: CHANG KUO WEI HERBERT (Director) Shares: 50 Est. Value: $71.0K
View on SEC EDGAR → Open Filing Document →
Form 4 Gift Tax / Compensation Filing 2026-08-06

MPWR insider Form 4 filed for equity award, exercise, or tax withholding

Sciammas Maurice (EVP, WW Sales & Marketing) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were transferred as a gift, typically for estate or charitable planning. No sale into the market took place.

Transactions reported on this filing
Code Nature Shares Price Value
G Gift 25,000 — —
G Gift 25,000 — —
Filing: Form 4 (Insider Transaction) Insider: Sciammas Maurice (EVP, WW Sales & Marketing) Shares: 50,000
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-06

MPWR insider DEAN ROBERT W II (Interim CFO) sold 105 shares (~$141.1K)

DEAN ROBERT W II, listed as Interim CFO at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 105 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 105 $1,344.27 $141.1K
Filing: Form 4 (Insider Transaction) Insider: DEAN ROBERT W II (Interim CFO) Shares: 105 Est. Value: $141.1K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-05

MPWR insider Sciammas Maurice (EVP, WW Sales & Marketing) sold 30 shares (~$40.3K)

Sciammas Maurice, listed as EVP, WW Sales & Marketing at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 30 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 30 $1,343.94 $40.3K
Filing: Form 4 (Insider Transaction) Insider: Sciammas Maurice (EVP, WW Sales & Marketing) Shares: 30 Est. Value: $40.3K
View on SEC EDGAR → Open Filing Document →
Form 4 Compensation award Tax / Compensation Filing 2026-07-28

MPWR insider Form 4 filed for equity award, exercise, or tax withholding

DEAN ROBERT W II (Interim CFO) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were granted as compensation rather than purchased. No cash changed hands, so the filing reflects a pay decision by the company, not a judgement about the price.

Transactions reported on this filing
Code Nature Shares Price Value
A Compensation award 1,359 — —
Filing: Form 4 (Insider Transaction) Insider: DEAN ROBERT W II (Interim CFO) Shares: 1,359
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-07-17

MPWR insider Sciammas Maurice (EVP, WW Sales & Marketing) sold 15,000 shares (~$20.25M)

Sciammas Maurice, listed as EVP, WW Sales & Marketing at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 15,000 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 527 $1,314.03 $692.5K
S Open-market sale 274 $1,318.42 $361.2K
S Open-market sale 409 $1,323.93 $541.5K
S Open-market sale 464 $1,329.30 $616.8K
S Open-market sale 776 $1,334.59 $1.04M
S Open-market sale 1,460 $1,339.59 $1.96M
S Open-market sale 1,864 $1,344.16 $2.51M
S Open-market sale 1,506 $1,348.91 $2.03M
S Open-market sale 5,640 $1,352.95 $7.63M
S Open-market sale 50 $1,359.36 $68.0K
S Open-market sale 240 $1,369.18 $328.6K
S Open-market sale 472 $1,375.47 $649.2K
S Open-market sale 418 $1,378.73 $576.3K
S Open-market sale 410 $1,384.11 $567.5K
S Open-market sale 50 $1,388.19 $69.4K
S Open-market sale 213 $1,396.16 $297.4K
S Open-market sale 117 $1,400.45 $163.9K
S Open-market sale 110 $1,405.71 $154.6K
Filing: Form 4 (Insider Transaction) Insider: Sciammas Maurice (EVP, WW Sales & Marketing) Shares: 15,000 Est. Value: $20.25M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-07-06

MPWR insider Sciammas Maurice (EVP, WW Sales & Marketing) sold 30 shares (~$40.5K)

Sciammas Maurice, listed as EVP, WW Sales & Marketing at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 30 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 30 $1,351.61 $40.5K
Filing: Form 4 (Insider Transaction) Insider: Sciammas Maurice (EVP, WW Sales & Marketing) Shares: 30 Est. Value: $40.5K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-06-03

MPWR insider Sciammas Maurice (EVP, WW Sales & Marketing) sold 30 shares (~$46.0K)

Sciammas Maurice, listed as EVP, WW Sales & Marketing at MONOLITHIC POWER SYSTEMS, INC., reported an open-market sale of 30 MPWR shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 30 $1,533.95 $46.0K
Filing: Form 4 (Insider Transaction) Insider: Sciammas Maurice (EVP, WW Sales & Marketing) Shares: 30 Est. Value: $46.0K
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 5 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. Monolithic Power Systems, Inc. has 5 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-08-24

MPWR Form 144 filed for proposed insider sale by DEAN ROBERT W II (32 shares) ~$83.1K

DEAN ROBERT W II filed a Form 144 with the SEC indicating intent to sell MPWR (MONOLITHIC POWER SYSTEMS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: DEAN ROBERT W II Shares: 32 Est. Value: $83.1K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-17

MPWR Form 144 filed for proposed insider sale by DEAN ROBERT W II (6 shares) ~$16.3K

DEAN ROBERT W II filed a Form 144 with the SEC indicating intent to sell MPWR (MONOLITHIC POWER SYSTEMS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: DEAN ROBERT W II Shares: 6 Est. Value: $16.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-11

MPWR Form 144 filed for proposed insider sale by Kuo Wei Chang (100 shares) ~$284.0K

Kuo Wei Chang filed a Form 144 with the SEC indicating intent to sell MPWR (MONOLITHIC POWER SYSTEMS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Kuo Wei Chang Shares: 100 Est. Value: $284.0K
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-05

MPWR Form 144 filed for proposed insider sale by ROBERT DEAN (105 shares) ~$282.3K

ROBERT DEAN filed a Form 144 with the SEC indicating intent to sell MPWR (MONOLITHIC POWER SYSTEMS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: ROBERT DEAN Shares: 105 Est. Value: $282.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-07-15

MPWR Form 144 filed for proposed insider sale by MAURICE SCIAMMAS (15,000 shares) ~$40.49M

MAURICE SCIAMMAS filed a Form 144 with the SEC indicating intent to sell MPWR (MONOLITHIC POWER SYSTEMS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: MAURICE SCIAMMAS Shares: 15,000 Est. Value: $40.49M
View on SEC EDGAR → Open Filing Document →
Material Events 2 · Form 8-K

An 8-K reports a material event in the window between scheduled reports. There are 2 in this period for Monolithic Power Systems, Inc. Each 8-K names the item number it is filed under, and that number is the fastest way to tell a routine disclosure from a consequential one.

Item 2.02 is an earnings release, Item 5.02 is a change of directors or officers, and Item 1.01 or 2.01 covers a material agreement or a completed acquisition. Item 7.01 and Item 8.01 are the general-purpose disclosure items and carry no fixed meaning on their own.

Form 8-K Material Company Update 2026-07-30

MPWR filed 8-K — material company event

MONOLITHIC POWER SYSTEMS, INC. filed an 8-K with the SEC reporting a material event. Filing excerpt: XBRL Viewer

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →
Form 8-K Material Company Update 2026-06-12

MPWR filed 8-K — material company event

MONOLITHIC POWER SYSTEMS, INC. filed an 8-K with the SEC reporting a material event. Filing excerpt: XBRL Viewer

Filing: 8-K (Material Event)
View on SEC EDGAR → Open Filing Document →
Periodic Reports 1 · Forms 10-K and 10-Q

The periodic reports are where the audited and reviewed financial statements live. This period contains 1 quarterly report (10-Q) for Monolithic Power Systems, Inc.

The two are not equivalent in weight. A 10-K is audited by an external firm and includes the full risk factor disclosure, business description and management discussion; a 10-Q is unaudited, reviewed rather than examined, and much shorter. When a figure in a quarterly report is later revised, the annual report is usually where the correction appears.

An amended report — 10-K/A or 10-Q/A — restates or corrects something in the original filing, and is worth reading against the version it replaces.

Form 10-Q Quarterly Report 2026-08-05

MPWR filed Quarterly Report (10-Q)

MONOLITHIC POWER SYSTEMS, INC. filed its quarterly report with the SEC. This report includes unaudited financial statements and management discussion for the quarter.

Filing: 10-Q (Quarterly Report)
View on SEC EDGAR → Open Filing Document →

How we classify Monolithic Power Systems, Inc.'s filings

Straight from EDGAR

Every filing on this page is pulled from the SEC's EDGAR system for Monolithic Power Systems, Inc. and parsed directly. Nothing here is estimated or inferred from a third-party feed, and each entry links back to the original document so the underlying filing can be read in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on MPWR. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MPWR SEC Filings

What SEC filings does Monolithic Power Systems, Inc. submit to the SEC?

Monolithic Power Systems, Inc. (MPWR) submits several types of SEC filings including Form 4 (insider transactions), Form 144 (proposed insider sales), 8-K reports (material events such as earnings releases, acquisitions, leadership changes), and periodic reports — the 10-Q (quarterly) and 10-K (annual). All filings are publicly available through SEC EDGAR.

What does a Form 4 filing tell me about MPWR?

A Form 4 for MPWR discloses a transaction by a company insider — typically a director, officer, or 10%+ shareholder. It shows the date, number of shares bought or sold, the price, and the insider's updated total ownership. Consistent insider buying across multiple executives is often interpreted as a bullish signal.

How do I interpret an 8-K filing from Monolithic Power Systems, Inc.?

An 8-K signals a material event requiring prompt disclosure. Common triggers include earnings pre-announcements, acquisitions, leadership appointments or departures, credit changes, or regulatory actions. Read the item codes inside the filing to understand exactly what was disclosed before drawing conclusions.

What is the difference between a 10-K and 10-Q for MPWR?

The 10-K is Monolithic Power Systems, Inc.'s annual report with fully audited financial statements, comprehensive MD&A, and complete risk factor disclosures — filed 60–90 days after fiscal year-end. The 10-Q is a lighter quarterly report with unaudited financials filed for the first three quarters. Together they provide a continuous financial picture of the company.

Where can I see all MPWR SEC filings directly on EDGAR?

You can view all historical Monolithic Power Systems, Inc. filings on the SEC EDGAR company page for MPWR. Each filing card on this page links directly to the original SEC document.

How often does Monolithic Power Systems, Inc. file with the SEC?

Monolithic Power Systems, Inc. files one 10-K per year and up to three 10-Qs per year. Form 4 insider transactions must be reported within two business days of each trade, so the frequency depends on how often insiders are buying or selling MPWR shares. 8-K filings occur whenever a material event happens — which can be several times per quarter for an active company.

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SEC filing data is sourced from SEC EDGAR. This page is updated automatically as new filings are detected. Content is for informational purposes only and does not constitute investment advice. Full Disclaimer.