Mr. Michael R. Hsing - 18 May 2026 Form 4 Insider Report for MONOLITHIC POWER SYSTEMS INC (MPWR)

Reporting relationship: CEO, Director
Issuer ticker: MPWR
Reported as of: 18 May 2026
Net transaction value: -$59,310,169
SEC form: 4
Accepted by SEC: 20 May 2026, 20:10:31 UTC
Prior SEC filing: 17 Feb 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 20 May 2026.

Key facts

This page summarizes Mr. Michael R. Hsing's Form 4 filing for MONOLITHIC POWER SYSTEMS INC (MPWR).
13 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 20 May 2026, 20:10.

Change

Previous filing in this sequence was filed on 17 Feb 2026.
Current net transaction value: -$59,310,169.

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: 20 May 2026

Reported non-derivative transactions

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

MPWR transaction

Common Stock

Sale

Transaction value: $5,007,977
Shares: -3,424
Change %: -0.39%
Price: $1462.61
Shares after: 884,839
Date: 18 May 2026
Ownership: Direct
Footnotes: F1, F2

MPWR transaction

Common Stock

Sale

Transaction value: $8,540,081
Shares: -5,819
Change %: -0.66%
Price: $1467.62
Shares after: 879,020
Date: 18 May 2026
Ownership: Direct
Footnotes: F3

MPWR transaction

Common Stock

Sale

Transaction value: $7,436,369
Shares: -5,049
Change %: -0.57%
Price: $1472.84
Shares after: 873,971
Date: 18 May 2026
Ownership: Direct
Footnotes: F4

MPWR transaction

Common Stock

Sale

Transaction value: $6,028,951
Shares: -4,082
Change %: -0.47%
Price: $1476.96
Shares after: 869,889
Date: 18 May 2026
Ownership: Direct
Footnotes: F5

MPWR transaction

Common Stock

Sale

Transaction value: $8,505,160
Shares: -5,737
Change %: -0.66%
Price: $1482.51
Shares after: 864,152
Date: 18 May 2026
Ownership: Direct
Footnotes: F6

MPWR transaction

Common Stock

Sale

Transaction value: $9,943,451
Shares: -6,688
Change %: -0.77%
Price: $1486.76
Shares after: 857,464
Date: 18 May 2026
Ownership: Direct
Footnotes: F7

MPWR transaction

Common Stock

Sale

Transaction value: $1,285,656
Shares: -862
Change %: -0.1%
Price: $1491.48
Shares after: 856,602
Date: 18 May 2026
Ownership: Direct
Footnotes: F8

MPWR transaction

Common Stock

Sale

Transaction value: $911,672
Shares: -608
Change %: -0.07%
Price: $1499.46
Shares after: 855,994
Date: 18 May 2026
Ownership: Direct
Footnotes: F9

MPWR transaction

Common Stock

Sale

Transaction value: $4,402,433
Shares: -2,929
Change %: -0.34%
Price: $1503.05
Shares after: 853,065
Date: 18 May 2026
Ownership: Direct
Footnotes: F10

MPWR transaction

Common Stock

Sale

Transaction value: $5,682,521
Shares: -3,769
Change %: -0.44%
Price: $1507.70
Shares after: 849,296
Date: 18 May 2026
Ownership: Direct
Footnotes: F11

MPWR transaction

Common Stock

Sale

Transaction value: $833,724
Shares: -551
Change %: -0.06%
Price: $1513.11
Shares after: 848,745
Date: 18 May 2026
Ownership: Direct
Footnotes: F12

MPWR transaction

Common Stock

Sale

Transaction value: $534,389
Shares: -352
Change %: -0.04%
Price: $1518.15
Shares after: 848,393
Date: 18 May 2026
Ownership: Direct
Footnotes: F13

MPWR transaction

Common Stock

Sale

Transaction value: $197,786
Shares: -130
Change %: -0.02%
Price: $1521.43
Shares after: 848,263
Date: 18 May 2026
Ownership: Direct
Footnotes: F14

MPWR holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 133,040
Date: 18 May 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: 18 May 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

Explanation of responses 14 footnotes

Footnote F1

Ending balance includes 29 shares acquired on February 17, 2026 through the Company's qualified ESPP program.

Footnote F2

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 $1,459.96 to $1,464.86. 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 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 $1,464.97 to $1,469.94. 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 $1,469.95 to $1,474.94. 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 $1,474.95 to $1,479.85. 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 $1,479.99 to $1,484.93. 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 $1,484.95 to $1,489.73. 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 $1,490.17 to $1,494.10. 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 $,1495.74 to $1,500.72. 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 $1,500.75 to $1,505.70. 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 F11

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 $1,505.70 to $1,510.67. 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 F12

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 $1,510.68 to $1,515.44. 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 F13

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 $1,516.26 to $1,519.25. 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 F14

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 $1,521.33 to $1,521.56. 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.