Insider trade

Director sold ~$266K of MPWR shares in the open market

Traded Dec 24, 2025 · Filed Dec 29, 2025

~$266K
Reported value · 280 sh @ $950.64: 29K
Holds after · shares reported: +42.8%
stock since the trade · S&P 500 +10.7%, $953.25 → $1,360.97 on Oct 1

Why it stands out

A board member of Monolithic Power Systems sold $266K of Monolithic Power Systems shares. It was planned long ago, so it says very little.

Written from the filing's own figures. OQRO describes what was reported and never tells you what to buy or sell

View the official recordSEC Form 4 — Statement of Changes in Beneficial Ownership

All the details

Dates, kept separate

Transaction date: Dec 24, 2025
Reporting period: Not applicable
Filed with the SEC: Dec 29, 2025

Director$100K–$500KPre-arranged plan referenced

Context

Classification

open market sale

Code S — open-market or private sale

Absolute commitment

~$266,179

Shares × reported transaction price

Timing vs results

55 days after results of Oct 30, 2025, 43 days before results of Feb 5, 2026

Results dates are the company's own 8-K (Item 2.02). Many companies only let insiders trade in a window after results

Price at the time

Closed at $953.25 on Dec 24, 2025, 109% above its 52-week low and 14% below its high, little changed over the previous 30 trading days

52-week range $455.19 (Apr 8, 2025) to $1,105.05 (Oct 27, 2025), 77% of the way up, from 250 adjusted closes. 30 trading days earlier: $954.71 on Nov 11, 2025. Describes the past only, not a forecast

Planned / mechanical clue

Footnote references a pre-arranged trading plan (Rule 10b5-1)

Only flagged when a footnote says so; never inferred

Securities lawsuit open at the trade date

A securities lawsuit naming the company as a defendant was filed on Feb 4, 2025 in the U.S. District Court, W.D. Washington. A filing is an allegation, not a finding.

Waterford Township General Employees Retirement System v. Monolithic Power Systems Inc, docket 2:25-cv-00220, via CourtListener (court records). Nature of suit 850, company named as first defendant

After it was reported

After	Stock	S&P 500	Difference
7 days	+8.8%	+0.7%	+8.1%
30 days	+28.1%	+1.0%	+27.0%
90 days	+8.5%	-8.0%	+16.5%
180 days	+42.1%	+7.9%	+34.2%

Past results only. Not a forecast.

Source receipt

Record ID: 0001214659-25-018478
Filed / recorded: Dec 29, 2025, 3:31 PM UTC
Added to OQRO: Oct 2, 2026, 12:28 PM UTC
Parser: form4-xml-v1
Data quality: Verified: identifiers matched exactly
Issuer: MONOLITHIC POWER SYSTEMS INC
Issuer CIK: 1280452
Ticker: MPWR
Reporting person: Victor K Lee
Relationship: Director
Security: Common Stock
Table: Non-derivative (Table I)
Transaction date: Dec 24, 2025
Transaction code: S
Shares / units: 280
Price per share: $950.64
Acquired / disposed: Disposed (D)
Shares owned after: 29,090
Ownership form: Direct
Amendment: No

Footnotes from the filing

These transactions were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 8/25/2025.
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 $950.30 to $950.90. 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.

Around the same time

Director sold ~$559K of Monolithic Power Systems

Scheduled in advance9mo ago

CFO sold ~$74K of Monolithic Power Systems

Scheduled in advance9mo ago

CFO sold ~$181K of Monolithic Power Systems

Scheduled in advance9mo ago