Mr. Michael R. Hsing - 28 Sep 2026 Form 4 Insider Report for MONOLITHIC POWER SYSTEMS, INC. (MPWR)

Reporting relationship: CEO, Director
Issuer ticker: MPWR
Reported as of: 28 Sep 2026
Net transaction value: -$40,349,047
SEC form: 4
Accepted by SEC: 30 Sep 2026, 17:21:16 UTC
Prior SEC filing: 20 May 2026
Source filing: View source filing
Reporting owner signature: /s/ Saria Tseng, attorney-in-fact for Mr. Michael R. Hsing

Key filing fact

Mr. Michael R. Hsing filed Form 4 for MONOLITHIC POWER SYSTEMS, INC. (MPWR) on 30 Sep 2026.

Key facts

This page summarizes Mr. Michael R. Hsing's Form 4 filing for MONOLITHIC POWER SYSTEMS, INC. (MPWR).
8 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 30 Sep 2026, 17:21.

Change

Previous filing in this sequence was filed on 20 May 2026.
Current net transaction value: -$40,349,047.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001308676 Primary reporting owner

Hsing Michael

Relationship: CEO, Director
Address: 1555 PALM BEACH LAKES BLVD., WEST PALM BEACH
Signature: /s/ Saria Tseng, attorney-in-fact for Mr. Michael R. Hsing
Signature date: 30 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MPWR transaction

Common Stock

Sale

Transaction value: $788,693
Shares: -596
Change %: -0.07%
Price: $1323.31
Shares after: 847,668
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F2, F3

MPWR transaction

Common Stock

Sale

Transaction value: $2,817,833
Shares: -2,121
Change %: -0.25%
Price: $1328.54
Shares after: 845,547
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F4

MPWR transaction

Common Stock

Sale

Transaction value: $1,481,341
Shares: -1,111
Change %: -0.13%
Price: $1333.34
Shares after: 844,436
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F5

MPWR transaction

Common Stock

Sale

Transaction value: $3,947,708
Shares: -2,949
Change %: -0.35%
Price: $1338.66
Shares after: 841,487
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F6

MPWR transaction

Common Stock

Sale

Transaction value: $7,770,964
Shares: -5,783
Change %: -0.69%
Price: $1343.76
Shares after: 835,704
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F7

MPWR transaction

Common Stock

Sale

Transaction value: $8,544,972
Shares: -6,343
Change %: -0.76%
Price: $1347.15
Shares after: 829,361
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F8

MPWR transaction

Common Stock

Sale

Transaction value: $14,821,133
Shares: -10,967
Change %: -1.3%
Price: $1351.43
Shares after: 818,394
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F9

MPWR transaction

Common Stock

Sale

Transaction value: $176,402
Shares: -130
Change %: -0.02%
Price: $1356.94
Shares after: 818,264
Date: 28 Sep 2026
Ownership: Direct
Footnotes: F1, F10

MPWR holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 133,040
Date: 28 Sep 2026
Ownership: by M Hsing 04 Trust

MPWR holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 12,825
Date: 28 Sep 2026
Ownership: ZH Family 2020 Trust

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 10 footnotes

Footnote F1

These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 05/29/2026.

Footnote F2

Ending balance includes 1 share acquired on August 17, 2026, through the Company's qualified ESPP program.

Footnote F3

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,320.64 to $1,325.61. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F4

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,325.65 to $1,330.62. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F5

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,330.65 to $1,335.51. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F6

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,335.68 to $1,340.66. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F7

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,340.69 to $1,345.65. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F8

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,345.66 to $1,350.47. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F9

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,350.84 to $1,355.11. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.

Footnote F10

The price is the weighted average sale price for the transactions reported on this line. The prices for the transactions reported on this line range from $1,356.78 to $1,357.00. The reporting person undertakes to provide, upon request by the staff of the Securities and Exchange Commission, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price.