Derrell Porter is VP at Atara Biotherapeutics, Inc. (ATRA). They have made 4 open-market trades across 2 companies since 2018, most recently 2026-06-17.
CIK 0001706400
Unrated. We grade insiders only on stock they chose to buy on the open market. Grants, option exercises and vesting say nothing about timing, so they don't count — which is why someone can file often and still have no grade. It isn't a bad sign: unrated buys beat every graded tier below A.
0 open-market purchases, against 4 sales. Too few scored purchases to measure a record yet.
| Ticker | Shares | Value |
|---|---|---|
| ATRA | 31,688 | $302K |
| ABOS | 35,500 | $60K |
| Total | $362K |
Shares reported on the most recent Form 4, priced at the 2026-06-17 close.
Counted per filing, not per execution lot — a purchase filled in several tranches is one decision.
Grouped by shared companies and similar filing behaviour. This is a similarity measure, not a ranking or a performance signal.