MarketPeel
Insider Trading Intelligence
WH

William K. Heiden

ATRA
DIRECTOR · ATARA BIOTHERAPEUTICS, INC. · CIK 0001214939
FILING MIX · LIFETIME90%/10%
BUYS
26
SELLS
3
TOTAL VALUE
$175.8K
COMPANIES
2
ACTIVE SINCE
Jun 2020
HOLDINGS NOW
37,938
AVG SELL PX
TRADE KIND
SHOWING 29 / 29
Trades · vs SPY
Loading price series…
Performance · forward returns vs SPY
3 backtested trades · 8 horizons · 4 pending
Forward-return performance of every backtestable P/S trade by William K. Heiden, measured at 8 horizons from 7 days to 2 years. Deduped per economic event so co-filings count once. Excess return = trade return minus SPY return over the same window.
HORIZONTRADESWIN RATEINSIDER RETURNSPY RETURNMEAN EXCESSMEDIAN EXCESST-STAT
7d3+100.00%+52.95%+1.49%+51.45%+20.64%
14d3+100.00%+76.19%+1.43%+74.76%+27.31%
30d3+100.00%+70.71%+4.12%+66.58%+12.60%
60d3+100.00%+59.58%+5.68%+53.90%+9.56%
90d3+100.00%+88.03%+7.01%+81.02%-0.09%
180d3+100.00%+58.31%+10.60%+47.72%+8.21%
1y3(2 pending)+100.00%+96.87%+37.60%+59.27%+59.27%
2y3(2 pending)+100.00%+114.10%+57.75%+56.35%+56.35%
How to read this: Insider Returnis the average raw return of the filer's trades over the horizon. SPY Return is what SPY did over those same windows — reference only, not a comparison. The headline alpha number is Mean Excess = Insider − SPY; green means the filer beat SPY, red means they trailed it. Win rate is the share of individual trades where the filer beat SPY. T-statvalues above 2 mean the alpha is unlikely to be chance given the sample size. "Pending" counts trades where the horizon hasn't elapsed yet; their stats are not included in the row average.
Holdings over time
ATRA · 34,188 shares · as of Jun 9, 2026
089,750179,500269,250359,000202120222023202420252026SHARES HELD
Trading cadence · quarterly flow
BUY SELL
2020
2020
2020
2021
2021
2021
2021
2022
2022
2022
2022
2023
2023
2023
2023
2024
2024
2024
2024
2025
2025
2025
2025
2026
2026
FLOW · 26 buys / 3 sellsCOVERAGE · 25 quarters
Form 4 filings · all activity
COMPANYTYPESHARESPRICEVALUEHELD AFTERTRADE DATEFILEDDETAILS
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
12,00034,188Jun 9, 2026Jun 11, 2026View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
3,7503,750May 19, 2026May 20, 2026View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
22,00022,000May 19, 2026May 20, 2026View →
MGNX
MACROGENICS INC
PURCHASE
3,750114,750May 18, 2026May 20, 2026View →
MGNX
MACROGENICS INC
SALE
3,7500May 18, 2026May 20, 2026View →
MGNX
MACROGENICS INC
PURCHASE
49,500$1.49$73.8K111,000Aug 20, 2025Aug 21, 2025View →
MGNX
MACROGENICS INC
PURCHASE
50,500$1.52$76.8K61,500Aug 19, 2025Aug 21, 2025View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
7,82822,188Jun 10, 2025Jun 12, 2025View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
3,7503,750May 21, 2025May 22, 2025View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
22,00022,000May 21, 2025May 22, 2025View →
MGNX
MACROGENICS INC
PURCHASE
6,50011,000May 20, 2025May 22, 2025View →
MGNX
MACROGENICS INC
SALE
6,5000May 20, 2025May 22, 2025View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
6,5006,500May 21, 2024May 23, 2024View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
16,50016,500May 21, 2024May 23, 2024View →
MGNX
MACROGENICS INC
SALE
4,5000May 20, 2024May 22, 2024View →
MGNX
MACROGENICS INC
PURCHASE
4,5004,500May 20, 2024May 22, 2024View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
150,000359,000Mar 31, 2024Apr 2, 2024View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASE
100,000$0.25$25.3K209,000Nov 10, 2023Nov 14, 2023View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
19,00019,000May 31, 2023Jun 2, 2023View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
4,5004,500May 31, 2023Jun 2, 2023View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
79,50079,500May 31, 2023Jun 2, 2023View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
57,000109,000May 31, 2023Jun 2, 2023View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
31,50031,500Jun 23, 2022Jun 27, 2022View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
20,50052,000Jun 23, 2022Jun 27, 2022View →
MGNX
MACROGENICS INC
PURCHASEGRANT
Stock grant
36,00036,000May 23, 2022May 24, 2022View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
17,50017,500Jun 8, 2021Jun 9, 2021View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
11,00031,500Jun 8, 2021Jun 9, 2021View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
8,00020,500Jun 16, 2020Jun 17, 2020View →
ATRA
ATARA BIOTHERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
24,50024,500Jun 16, 2020Jun 17, 2020View →
Other insiders · ATRA
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About this filer
CIK 0001214939
ROLE
Director
PRIMARY
ATRA
COMPANIES
2
ACTIVE SINCE
Jun 2020
MARKETPEEL · /INSIDER/0001214939DATA · SEC EDGAR · FORM 4 · CONSOLIDATED TAPE
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