Insider trade

CEO sold ~$534K of MPWR shares in the open market

Traded May 18, 2026 · Filed May 21, 2026

Monolithic Power SystemsMPWR

~$534K
Reported value · 352 sh @ $1,518.15: 848K
Holds after · shares reported: -8.4%
stock since the trade · S&P 500 +3.4%, $1,486.33 → $1,360.97 on Oct 1

Why it stands out

The boss of Monolithic Power Systems sold $534K of Monolithic Power Systems shares. Nobody planned it ahead of time.

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: May 18, 2026
Reporting period: Not applicable
Filed with the SEC: May 21, 2026

CEO$500K–$1M

Context

Classification

open market sale

Code S — open-market or private sale

Absolute commitment

~$534,389

Shares × reported transaction price

Timing vs results

18 days after results of Apr 30, 2026, 73 days before results of Jul 30, 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 $1,486.33 on May 18, 2026, 125% above its 52-week low and 11% below its high, after a 26% rise over the previous 30 trading days

52-week range $661.90 (May 30, 2025) to $1,661.10 (May 11, 2026), 83% of the way up, from 251 adjusted closes. 30 trading days earlier: $1,180.03 on Apr 6, 2026. Describes the past only, not a forecast

Planned / mechanical clue

None found in footnotes

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	+4.6%	+1.6%	+3.0%
30 days	-1.5%	+0.2%	-1.7%
90 days	-16.7%	+3.5%	-20.3%

Past results only. Not a forecast.

Source receipt

Record ID: 0001214659-26-006625
Filed / recorded: May 21, 2026, 12:10 AM 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: Michael Hsing
Relationship: Director, Officer
Officer title: CEO
Security: Common Stock
Table: Non-derivative (Table I)
Transaction date: May 18, 2026
Transaction code: S
Shares / units: 352
Price per share: $1,518.15
Acquired / disposed: Disposed (D)
Shares owned after: 848,393
Ownership form: Direct
Amendment: No

Footnotes from the filing

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.