Key facts
- William C. Kirby has 2 issuer positions tracked on this page.
- Estimated disclosed ownership value: $2,022,464.
- Recent insider filing activity is available below.
Insider Trading & Ownership of William C. Kirby
- Location
- Lexington, MA
- Summary
- The estimated net worth of William C. Kirby is at least $2,022,464 dollars as of 27 Feb 2026. William C. Kirby is the Director of CABOT CORP and owns shares of CABOT CORP (CBT) stock worth about $1.84M. William C. Kirby is the Director of TAIWAN FUND INC and owns shares of TAIWAN FUND INC (TWN) stock worth about $187.3K.
- Signature
- /s/ William C. Kirby
- All Insider Reports
- All Insider Reports
Follow Filing Activity
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Change
- Largest disclosed position: CABOT CORP ($1,835,163).
- Past-year value change for that position: .
Research use
- This page translates Forms 3/4/5 into a quick ownership context before you inspect each transaction row.
- You can cross-check role, issuer, and filing chronology directly against the SEC source.
Evidence
Filed on Form 4
See Original Filing
Insider ownership context is sourced from SEC Forms 3, 4, and 5.
Ownership of William C. Kirby
CBT
Forms 3/4/5
CABOT CORP
- Relationship
- Director
- Holdings value
- $1,835,163
- Past year net change
- Change %
- Report period
- 08 Jan 2026
TWN
Forms 3/4/5
TAIWAN FUND INC
- Relationship
- Director
- Holdings value
- $187,301
- Past year net change
- +$3,289,580
- Change %
- +1756%
- Report period
- 26 Feb 2026
Insider Transactions Reported by William C. Kirby:
| Sym | Company | Class | Transaction | % | Value $ | * Price $ | Shares | Shares After | Date | Ownership |
|---|
* An asterisk sign (*) next to the price indicates that the price is likely invalid.