=== SEC Form 4 — Statement of Changes in Beneficial Ownership ===
Document Type: 4
Period of Report: 2026-02-12
10b5-1 Pre-arranged Plan: Yes
--- Issuer ---
Name: MONOLITHIC POWER SYSTEMS INC (MPWR)
CIK: 0001280452
--- Reporting Owner ---
Name: Hsing Michael
CIK: 0001308676
Role: Director, Officer (CEO)
--- Non-Derivative Transactions ---
[Transaction #1]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -12,731 | Price: $1,155.71
Total Value: $14,713,344.01
Shares Owned After: 908,503 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,152.31 to $1,157.31. 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.
[Transaction #2]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -4,992 | Price: $1,159.84
Total Value: $5,789,921.28
Shares Owned After: 903,511 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,157.38 to $1,162.38. 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.
[Transaction #3]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -4,001 | Price: $1,164.92
Total Value: $4,660,844.92
Shares Owned After: 899,510 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,162.42 to $1,167.20 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.
[Transaction #4]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -2,076 | Price: $1,168.80
Total Value: $2,426,428.80
Shares Owned After: 897,434 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,167.43 to $1,172.17. 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.
[Transaction #5]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -200 | Price: $1,173.39
Total Value: $234,678.00
Shares Owned After: 897,234 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,172.82 to $1,175.07. 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.
[Transaction #6]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -480 | Price: $1,180.79
Total Value: $566,779.20
Shares Owned After: 896,754 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,179.43 to $1,182.24. 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.
[Transaction #7]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -160 | Price: $1,188.23
Total Value: $190,116.80
Shares Owned After: 896,594 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,185.94 to $1,190.48. 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.
[Transaction #8]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -600 | Price: $1,194.34
Total Value: $716,604.00
Shares Owned After: 895,994 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,191.26 to $1,195.35. 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.
[Transaction #9]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -1,440 | Price: $1,200.81
Total Value: $1,729,166.40
Shares Owned After: 894,554 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,197.57 to $1,202.33. 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.
[Transaction #10]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -3,640 | Price: $1,205.82
Total Value: $4,389,184.80
Shares Owned After: 890,914 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,202.70 to $1,207.63. 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.
[Transaction #11]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -1,240 | Price: $1,210.11
Total Value: $1,500,536.40
Shares Owned After: 889,674 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,207.93 to $1,212.36. 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.
[Transaction #12]
Security: Common Stock
Date: 2026-02-12 | Code: S (Open market sale)
Shares: -1,440 | Price: $1,217.12
Total Value: $1,752,652.80
Shares Owned After: 888,234 | Ownership: D (Direct)
Footnotes:
[F1] These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
[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 $1,214.09 to $1,218.82. 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.
--- Holdings ---
[Holding #1]
Security: Common Stock
Ownership: I (Indirect)
[Holding #2]
Security: Common Stock
Ownership: I (Indirect)
--- Footnotes (Complete Index) ---
F1: These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 08/28/2025.
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 $1,197.57 to $1,202.33. 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.
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 $1,202.70 to $1,207.63. 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.
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 $1,207.93 to $1,212.36. 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.
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 $1,214.09 to $1,218.82. 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.
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 $1,152.31 to $1,157.31. 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.
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 $1,157.38 to $1,162.38. 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.
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 $1,162.42 to $1,167.20 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.
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 $1,167.43 to $1,172.17. 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.
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 $1,172.82 to $1,175.07. 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.
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 $1,179.43 to $1,182.24. 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.
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 $1,185.94 to $1,190.48. 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.
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 $1,191.26 to $1,195.35. 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.
--- Signature ---
/s/ /s/ Saria Tseng, attorney-in-fact for Mr. Michael R. Hsing (2026-02-17)
