InsiderSource

Doberstein Stephen K

Director, SVP & Chief Scientific Officer, Chief Scientific Officer · SEC CIK 1480111
Insider at FBRX Forte Biosciences, Inc. DRNA Dicerna Pharmaceuticals Inc NKTR NEKTAR THERAPEUTICS

Buy track record

How this insider's open-market purchases have performed
0%
of buys now in profit
0 up · 1 down
Avg return since buy−77.2%
Median return−77.2%
Best trade−77.2%
Worst trade−77.2%
Buys scored1
Average return by holding period — separates good entry timing from riding one long winner
After 1 month +7.5% 100% won · 1 trade
After 3 months +14.3% 100% won · 1 trade
After 6 months +16.0% 100% won · 1 trade
After 12 months +6.2% 100% won · 1 trade
DateCompany90d trendBuy priceValueΔOwn1M3M6M12MTo date
Sep 5, 2019 NKTR $17 $259.2K +16% +7.5% +14.3% +16.0% +6.2% −77.2%
How this is calculated. We score only open-market purchases (SEC code P) — the buys that carry real signal. Each trade's return is measured from the adjusted closing price on the purchase date to the latest close, accounting for stock splits and dividends. The 1M/3M/6M/12M columns show the same trade's return after each fixed holding period; a dash means that horizon hasn't elapsed yet or isn't priceable. Sales are excluded because insiders sell for many routine reasons. With only 1 scored trade, treat this as a small sample, not a verdict.
Open-market buys
$259.2K
1 trades
Open-market sells
$30.74M
20 trades
Net flow
−$30.48M
Net selling
Total filings
42
transactions shown

Full transaction history

All Form 4 activity across every company, newest first
View on SEC EDGAR ↗
NKTR
NEKTAR THERAPEUTICS
Buy Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market purchase · filed Sep 9, 2019 ΔOwn +16%

Doberstein Stephen K, NKTR's SVP & Chief Scien…, spent $259.2K of their own money on 15,000 shares at $17, growing their stake 16%.

+$259.2K
15,000 sh @ $17
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Aug 19, 2019 ΔOwn −3.4%

Doberstein Stephen K sold $58.9K of NKTR, trimming their stake 3%.

−$58.9K
3,245 sh @ $18
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed May 17, 2019 ΔOwn −3.5%

Doberstein Stephen K sold $108.6K of NKTR, trimming their stake 3%.

−$108.6K
3,461 sh @ $31
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Feb 21, 2019 ΔOwn −3.2%

Doberstein Stephen K sold $140.3K of NKTR, trimming their stake 3%.

−$140.3K
3,310 sh @ $42
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Nov 19, 2018 ΔOwn −5.4%

Doberstein Stephen K sold $173K of NKTR, trimming their stake 5%.

−$173K
4,524 sh @ $38
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed May 18, 2018 ΔOwn −5.1%

Doberstein Stephen K sold $286.4K of NKTR, trimming their stake 5%.

−$286.4K
3,435 sh @ $83
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Apr 9, 2018 ΔOwn −42%

Doberstein Stephen K sold $4.76M of NKTR, trimming their stake 42%.

−$4.76M
49,500 sh @ $96
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Apr 9, 2018 ΔOwn −62%

Doberstein Stephen K sold $10.13M of NKTR, trimming their stake 62%.

−$10.13M
110,500 sh @ $92
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Feb 20, 2018 ΔOwn −3.5%

Doberstein Stephen K sold $201.2K of NKTR, trimming their stake 3%.

−$201.2K
2,426 sh @ $83
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Nov 8, 2017 ΔOwn −91%

Doberstein Stephen K sold $9.03M of NKTR, trimming their stake 91%.

−$9.03M
300,000 sh @ $30
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Nov 8, 2017 ΔOwn −71%

Doberstein Stephen K sold $1.94M of NKTR, trimming their stake 71%.

−$1.94M
75,409 sh @ $26
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Nov 8, 2017 ΔOwn −40%

Doberstein Stephen K sold $522.4K of NKTR, trimming their stake 40%.

−$522.4K
20,914 sh @ $25
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Oct 10, 2017 ΔOwn −58%

Doberstein Stephen K sold $1.09M of NKTR, trimming their stake 58%.

−$1.09M
43,677 sh @ $25
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Aug 18, 2017 ΔOwn −5.2%

Doberstein Stephen K sold $32.9K of NKTR, trimming their stake 5%.

−$32.9K
1,701 sh @ $19
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed May 18, 2017 ΔOwn −4.9%

Doberstein Stephen K sold $33.3K of NKTR, trimming their stake 5%.

−$33.3K
1,701 sh @ $20
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Apr 7, 2017 ΔOwn −74%

Doberstein Stephen K sold $2.17M of NKTR, trimming their stake 74%.

−$2.17M
100,000 sh @ $22
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Feb 17, 2017 ΔOwn −3.5%

Doberstein Stephen K sold $16.6K of NKTR, trimming their stake 4%.

−$16.6K
1,261 sh @ $13
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Nov 18, 2016 ΔOwn −3.5%

Doberstein Stephen K sold $9.4K of NKTR, trimming their stake 4%.

−$9.4K
670 sh @ $14
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Aug 17, 2016 ΔOwn −6.6%

Doberstein Stephen K sold $23.5K of NKTR, trimming their stake 7%.

−$23.5K
1,336 sh @ $18
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed May 18, 2016 ΔOwn −25%

Doberstein Stephen K sold $4.6K of NKTR, trimming their stake 25%.

−$4.6K
339 sh @ $14
NKTR
NEKTAR THERAPEUTICS
Sell Doberstein Stephen K · SVP & Chief Scientific Officer · Open-market sale · filed Feb 18, 2016 ΔOwn −45%

Doberstein Stephen K sold $4.6K of NKTR, trimming their stake 45%.

−$4.6K
390 sh @ $12

Frequently asked questions

How is Doberstein Stephen K's win rate calculated?

We take every open-market purchase (SEC code P) we can match to a stock price, then compare the split- and dividend-adjusted price on the purchase date to the most recent close. The win rate is the share of those buys currently trading above the purchase price. Sales and share grants are not scored.

Why are some buys not included in the score?

A purchase is excluded if we can't price it — for example if the ticker is missing from the filing, the company has been delisted, or the security isn't a common stock we can match to market data. Excluded counts are shown next to the scored total.

What do the 1M / 3M / 6M / 12M columns mean?

They show each purchase's return after a fixed holding period — one, three, six, and twelve months from the buy date — using split- and dividend-adjusted prices. This separates good entry timing from simply holding a long-running winner. A dash means that horizon hasn't elapsed yet for that trade, or the stock couldn't be priced at that date.

Does a high win rate mean I should copy this insider?

No. Past performance does not predict future results, sample sizes are often small, and an insider's edge in their own company doesn't transfer to yours. This is context, not a recommendation. InsiderSource is not investment advice.

Where does this data come from?

Trades come from Doberstein Stephen K's SEC Form 4 filings on EDGAR. Prices come from public market data and are split/dividend-adjusted. Always verify against the original filings before acting.