Comparable stake leader
Jefferson Gramm
SEC ownership of Rubicon Technology, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001410172.
Disclosed value leader
Jefferson Gramm
Comparable rows
0/6
Latest evidence
22 Feb 2023
- Public ticker
- RBCN on OTC
- Parsed ownership sources
-
3/4/5
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Jefferson Gramm
Ranking: Comparable ownership first, then disclosed value
- Latest parsed ownership date
-
22 Feb 2023
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001410172
- Issuer location
- Bensenville, IL
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
1 signal
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Rubicon Technology, Inc. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Jefferson Gramm
Disclosed value leader
Jefferson Gramm
Comparable rows
0/6
Latest evidence
22 Feb 2023
3/4/5
Highest disclosed value: $3,025,083
6 rows are not safely comparable across share classes.
Quick read
Jefferson Gramm has the largest disclosed position value at $3.03M.
0 of 6 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Jefferson Gramm's linked filing trail.
Disclosed position value
Top 5
Jefferson Gramm
$3.03M
JANEL CORP
$1.67M
Darren Clay Seirer
$682.3K
MIKOLAJCZYK MICHAEL E
$47.5K
Timothy Brog
$7.5K
Value bars compare disclosed positions; verify each figure against the linked filing evidence.
Detailed SEC evidence table Showing 1-6 of 6 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Jefferson Gramm |
3/4/5
Director, Other*, 10%+ Owner
|
—
mixed-class rows
|
$3,025,083
395,054 shares
mixed-class rows
|
— | 19 Aug 2022 |
| JANEL CORP |
3/4/5
10%+ Owner
|
—
class O/S missing
|
$1,673,080
1,108,000 shares
|
— | 19 Aug 2022 |
| Darren Clay Seirer |
3/4/5
Director, 10%+ Owner
|
—
class O/S missing
|
$682,281
451,842 shares
|
— | 19 Aug 2022 |
| MIKOLAJCZYK MICHAEL E |
3/4/5
Director
|
—
class O/S missing
|
$47,499
31,456 shares
|
— | 19 Aug 2022 |
| Timothy Brog |
3/4/5
Director
|
—
class O/S missing
|
$7,503
4,969 shares
|
— | 22 Feb 2023 |
| Susan Westphal |
3/4/5
Director
|
—
class O/S missing
|
$6,668
4,416 shares
|
— | 19 Aug 2022 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Insider buy and sell flow is broadly balanced over the last 12 months. No Buy or Sell transactions have been reported since 21 Aug 2025.
Buys
$0
Insiders: 0
Sells
$0
Insiders: 0
Net
$0
Shares: 0
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 0
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-7 of 7 reporting-owner rows connected to Rubicon Technology, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
7
Largest Forms 3/4/5 holder
Jefferson Gramm
Net 12M change
$0
Latest report
22 Feb 2023
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Jefferson Gramm | Director, Other*, 10%+ Owner | $3,025,083 | Mixed | 19 Aug 2022 | ||
| JANEL CORP | 10%+ Owner | $1,673,080 | Mixed | 19 Aug 2022 | ||
| Darren Clay Seirer | Director, 10%+ Owner | $682,281 | Mixed | 19 Aug 2022 | ||
| MIKOLAJCZYK MICHAEL E | Director | $47,499 | Mixed | 19 Aug 2022 | ||
| Timothy Brog | Director | $7,503 | Filing P/S | 22 Feb 2023 | ||
| Susan Westphal | Director | $6,668 | Mixed | 19 Aug 2022 | ||
| John Eidinger | Director | Mixed | 19 Aug 2022 |
Recent insider transactions for Rubicon Technology, Inc.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| No insider transactions were found in the last 12 months for this issuer. | ||||||||||
* marks a reported price that did not pass the local price check.