Corporate insider
Donfris Michael J
GBXHoldLens InsiderScore
-31
Net insider selling
Buys
2
$0
Sells
5
$164K
Dominant
mixed
Confidence
78%
Transaction history
| Date | Action | Shares | Price | Value |
|---|---|---|---|---|
| Oct 22, 2026 | BUY | 1,026 | $0 | $0 |
| Oct 22, 2026 | SELL | 584 | $37.69 | $22K |
| Oct 22, 2026 | SELL | 1,026 | $0 | $0 |
| Oct 21, 2026 | SELL | 2,380 | $37.61 | $90K |
| Oct 21, 2026 | BUY | 21,254 | $0 | $0 |
| Oct 18, 2026 | SELL | 623 | $39.11 | $24K |
| Oct 17, 2026 | SELL | 724 | $39.11 | $28K |
Related
All GBX insiders
Every tracked officer at GBX — aggregate InsiderScore + all Form 4s.
GBX ConvictionScore
Full 13F + InsiderScore unified signal for GBX.
Live insider feed
Every tracked Form 4 across all companies, chronological.
Deep dive
Reading for your research
Optional background reading on interpreting company disclosures and investing methods. These books do not validate a signal or predict returns.
Amazon affiliate links — as an Amazon Associate, HoldLens earns from qualifying purchases and membership trials at no extra cost to you. These are books we genuinely recommend. Not investment advice; always do your own research.
Benjamin Graham
The Intelligent Investor
The foundational text. Buffett calls it 'by far the best book about investing ever written.'
See price on Amazon
Benjamin Graham & David Dodd
Security Analysis
The deep dive behind The Intelligent Investor — how to actually read a filing and value a business.
See price on Amazon
See the full investing reading list
More by topic:Foundations