REGN insider ownership: who sold, why, and what they still hold

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Marion McCourt EVP Commercial	1,131	$857.39	8.5%	12K	Sep 3, 2026	Sep 3, 2026

What stands out

Christine Poon sold $4.3M of stock with no disclosed trading plan. The filings don't state a reason.Largest such sale, Oct 29, 2025

Jason Pitofsky sold 51% of vested holdings: 2.5K shares for $1.9M, 85% under a disclosed plan.Largest sale, Feb 9, 2026

Tax withholding outweighed market sales: the company withheld $303M of officers' and directors' shares for taxes, against $12.9M sold on the open market. The largest was Leonard Schleifer ($131M withheld).Largest withholding, Dec 9, 2025

Percentages cover 13 of 19 officers and directors. 6 are left out

Left out: Leonard Schleifer and Daniel Van Plew (holdings couldn't be fully reconciled); Christine Poon, Bonnie Bassler, Huda Zoghbi and Kathryn Guarini (most of their shares vested during the period, so a percentage would mislead).

Disclosed company stock is not an insider's whole wealth.

Who sold, and how much of their stake

Officers and directors, past 12 months. Each bar is the insider's vested stake at the start of the period (Oct 8, 2025). The gold part is what they sold.

SoldRest of starting stakeAdded during the period

Christine Poon

Director

Sold 55% of the shares held or received (after tax withholding) during the period†. No bar against the starting stake: most of these shares arrived during the period.

$4.3MNo plan disclosed

Marion McCourt

EVP Commercial

16% · $2.0MDisclosed plan

Huda Zoghbi

Director

Sold 59% of the shares held or received (after tax withholding) during the period†. No bar against the starting stake: most of these shares arrived during the period.

$1.9MDisclosed plan

Jason Pitofsky

SVP Controller

51% · $1.9M85% planned

Bonnie Bassler

Director

Sold 57% of the shares held or received (after tax withholding) during the period†. No bar against the starting stake: most of these shares arrived during the period.

$1.8MDisclosed plan

All 7 sellers

Selling by month

Officers and directors, Oct 2025 to Oct 2026. Each sale is counted once: under a disclosed plan, else to cover taxes, else no plan disclosed.

Disclosed planTo cover taxesNo plan disclosed

Common questions

Is the Regeneron Pharmaceuticals CEO selling stock?

No. Leonard Schleifer reported no open-market sales in the past 12 months.

Why are Regeneron Pharmaceuticals insiders selling?

Filings rarely give a reason, and we don't guess at one. What they show is how the sales were made: 65% of sales by value ran under 10b5-1 trading plans disclosed in the filings and 35% had no disclosed plan. A trading plan schedules sales in advance.

Are any Regeneron Pharmaceuticals insiders buying?

No. Officers and directors reported no purchases in the past 12 months.

How much of their stake did Regeneron Pharmaceuticals insiders sell?

About 0.4% overall. As a group they ended with more shares than they started with. The biggest seller whose stake can be measured, Marion McCourt, gave up 16% of starting holdings. These figures leave out Leonard Schleifer, the largest holder (holdings couldn't be fully reconciled). That covers the 12 months to Oct 8, 2026 and counts vested shares reported on SEC Forms 3, 4 and 5, which is not an insider's whole wealth.

The evidence

Who sold7 officers and directors: amount, % of holdings, trading plan

Who sold	Amount	% of holdings	Trading plan
Christine Poon Director	$4.3M 6.5K shares	55%† i † Most of the shares Christine Poon sold arrived during the period, so this is shares sold as a share of the 2.4K held at the start plus the 9.4K received, less 0 withheld by the company for taxes.	No plan disclosed
Marion McCourt EVP Commercial	$2.0M 2.3K shares	16%	Disclosed plan
Huda Zoghbi Director	$1.9M 2.4K shares	59%† i † Most of the shares Huda Zoghbi sold arrived during the period, so this is shares sold as a share of the 1.5K held at the start plus the 2.6K received, less 0 withheld by the company for taxes.	Disclosed plan
Jason Pitofsky SVP Controller	$1.9M 2.5K shares	51%	85% under a disclosed plan
Bonnie Bassler Director	$1.8M 2.3K shares	57%† i † Most of the shares Bonnie Bassler sold arrived during the period, so this is shares sold as a share of the 1.5K held at the start plus the 2.4K received, less 0 withheld by the company for taxes.	Disclosed plan
Kathryn Guarini Director	$660K 800 shares	57%† i † Most of the shares Kathryn Guarini sold arrived during the period, so this is shares sold as a share of the 448 held at the start plus the 955 received, less 0 withheld by the company for taxes.	Disclosed plan
Arthur Ryan Director	$435K 600 shares	3.4%	Disclosed plan

The full ownership picture17 of 19 insiders fully reconciled · 19 officers and directors

Vested shares across all share classes, held directly and through trusts, LLCs and family members, as reported on SEC Forms 3, 4 and 5. Unvested awards and options are never counted as owned shares.

Insider

Held Oct 8, 2025

Sold

Held Oct 8, 2026

Still held

Leonard Schleifer

Holdings couldn't be fully reconciled. Balance changed with no matching transaction and no footnote: +300,000 shares on Dec 9, 2025 (2025 GRAT). See the filing Sales and other transactions for Leonard Schleifer are complete.

Bd. Co-Chair, President & CEO, Director

n/a

Vesting, gifts, unvested awards and holding lines for Leonard Schleifer

+201Kshares vested or exercised

0gifted (net of own trusts)

−184Kwithheld by the company for taxes

0 → 595Kunvested awards, start → end

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Holdings couldn't be fully reconciled. Balance changed with no matching transaction and no footnote: +300,000 shares on Dec 9, 2025 (2025 GRAT). The balances below are as reported, not verified totals.

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Class A Stock	1,710,790	1,710,790
Trust for Son	Class A Stock	14,775	14,775
Direct	Common Stock	466,877	214,523
2023 GRAT	Common Stock	157,552	157,552
Trust	Common Stock	39,985	39,985
401(k) Plan	Common Stock	5,932	5,989
2024 GRAT	Common Stock	0	127,484
2025 GRAT	Common Stock	0	300,000

Additional holdings last reported Dec 15, 2009, not confirmed since: 60,350 shares. Not included in any total or percentage on this page.

Son, Class A Stock: 29,275 shares, last reported Sep 13, 2009
Son 2, Class A Stock: 29,275 shares, last reported Sep 13, 2009
Son, Common Stock: 900 shares, last reported Dec 15, 2009
Son 2, Common Stock: 900 shares, last reported Sep 13, 2009

George Yancopoulos

Minor difference of 59 shares. Difference is under 0.5% of holdings. Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Bd. Co-Chair, President & CSO, Director

1.11M

1.13M

no sales

Vesting, gifts, unvested awards and holding lines for George Yancopoulos

+175Kshares vested or exercised

0gifted (net of own trusts)

−160Kwithheld by the company for taxes

0 → 595Kunvested awards, start → end

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	868,994	310,460
Trust for Chldn	Common Stock	180,000	180,000
Children	Common Stock	56,048	56,048
401(k) Plan	Common Stock	5,903	5,962
2024 GRAT	Common Stock	0	71,487
2025 GRAT	Common Stock	0	200,000
2025 GRAT II	Common Stock	0	200,000
2024 GRAT II	Common Stock	0	101,988

Additional holdings last reported Apr 15, 2021, not confirmed since: 542,750 shares. Not included in any total or percentage on this page.

Direct, Class A Stock: 23,367 shares, last reported Nov 18, 2019
Tr. for Daughter, Class A Stock: 14,000 shares, last reported Apr 15, 2021
Trust for Son, Class A Stock: 5,383 shares, last reported Apr 15, 2021
GRAT, Common Stock: 500,000 shares, last reported Dec 18, 2017

Reconciliation: minor difference of 59 shares. Difference is under 0.5% of holdings.

Andrew Murphy

Minor difference of 49 shares. Difference is under 0.5% of holdings.

EVP Research

53K

52K

no sales

Vesting, gifts, unvested awards and holding lines for Andrew Murphy

+35Kshares vested or exercised

−1.5Kgifted (net of own trusts)

−38Kwithheld by the company for taxes

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	49,074	47,833
401(k) Plan	Common Stock	4,326	4,375

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
11,473	$843.79	Dec 8, 2033	$156K
13,472	$771.64	Dec 6, 2034	$1.2M
18,315	$726.71	Dec 5, 2035	$2.4M

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Reconciliation: minor difference of 49 shares. Difference is under 0.5% of holdings.

Daniel Van Plew

Holdings couldn't be fully reconciled. Balance changed without a matching transaction, and the footnote does not state the amount: -12,376 shares on Dec 5, 2025 (Direct). See the filing Sales and other transactions for Daniel Van Plew are complete.

EVP & General Mgr, Industrial

n/a

Vesting, gifts, unvested awards and holding lines for Daniel Van Plew

0shares vested or exercised

0gifted (net of own trusts)

−4.5Kwithheld by the company for taxes

none reportedunvested awards, start → end

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Holdings couldn't be fully reconciled. Balance changed without a matching transaction, and the footnote does not state the amount: -12,376 shares on Dec 5, 2025 (Direct). The balances below are as reported, not verified totals.

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	34,792	21,673
2025 GRAT	Common Stock	12,376	12,376
401(k) Plan	Common Stock	1,100	1,129

Additional holdings last reported May 18, 2016, not confirmed since: 18,705 shares. Not included in any total or percentage on this page.

GRAT, Common Stock: 18,705 shares, last reported May 18, 2016

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
12,250	$372.46	Dec 11, 2029	$5.9M
11,473	$843.79	Dec 8, 2033	$156K
13,472	$771.64	Dec 6, 2034	$1.2M
18,315	$726.71	Dec 5, 2035	$2.4M

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Joseph Larosa

Minor difference of 42 shares. Difference is under 0.5% of holdings.

EVP General Counsel and Secret

39K

46K

no sales

Vesting, gifts, unvested awards and holding lines for Joseph Larosa

+27Kshares vested or exercised

0gifted (net of own trusts)

−23Kwithheld by the company for taxes

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	30,075	36,373
2024 GRAT	Common Stock	9,000	3,402
401(k) Plan	Common Stock	371	413
2025 GRAT	Common Stock	0	5,407

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
12,283	$381.92	Dec 16, 2026	$5.8M
7,649	$843.79	Dec 8, 2033	$104K
8,981	$771.64	Dec 6, 2034	$770K
12,210	$726.71	Dec 5, 2035	$1.6M

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Reconciliation: minor difference of 42 shares. Difference is under 0.5% of holdings.

George Sing

Director

30K

33K

no sales

Vesting, gifts, unvested awards and holding lines for George Sing

+9.2Kshares vested or exercised

0gifted (net of own trusts)

−6.2Kwithheld by the company for taxes

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	27,828	31,007
Trust for Son	Common Stock	1,000	1,000
Spouse	Common Stock	750	750
Spouse/Cust Son	Common Stock	400	400

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Christopher Fenimore

Minor difference of 59 shares. Difference is under 0.5% of holdings. Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

EVP Finance CFO

20K

24K

no sales

Vesting, gifts, unvested awards and holding lines for Christopher Fenimore

+6.3Kshares vested or exercised

0gifted (net of own trusts)

−5.6Kwithheld by the company for taxes

none reportedunvested awards, start → end

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	16,265	19,984
Trust	Common Stock	1,897	1,897
401(k) Plan	Common Stock	1,515	1,574
Trust for Daugh	Common Stock	25	25
Trust for Son	Common Stock	25	25

Additional holdings last reported Aug 30, 2018, not confirmed since: 2,695 shares. Not included in any total or percentage on this page.

GRAT, Common Stock: 2,695 shares, last reported Aug 30, 2018

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
6,000	$381.92	Dec 16, 2026	$2.9M
8,499	$843.79	Dec 8, 2033	$116K
9,979	$771.64	Dec 6, 2034	$856K
14,924	$726.71	Dec 5, 2035	$2.0M

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Reconciliation: minor difference of 59 shares. Difference is under 0.5% of holdings.

Arthur Ryan

Director

18K

−600

17K

97%

Vesting, gifts, unvested awards and holding lines for Arthur Ryan

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	17,748	17,303

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Marion McCourt

Minor difference of 45 shares. Difference is under 0.5% of holdings.

EVP Commercial

14K

−2.3K

12K

85%

Vesting, gifts, unvested awards and holding lines for Marion McCourt

0shares vested or exercised

0gifted (net of own trusts)

−2.4Kwithheld by the company for taxes

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	14,230	12,003
401(k) Plan	Common Stock	174	219

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
6,000	$381.40	Dec 12, 2028	$2.9M
7,649	$843.79	Dec 8, 2033	$104K
8,981	$771.64	Dec 6, 2034	$770K
12,210	$726.71	Dec 5, 2035	$1.6M

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Reconciliation: minor difference of 45 shares. Difference is under 0.5% of holdings.

Michael Brown

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Director

13K

no sales

Vesting, gifts, unvested awards and holding lines for Michael Brown

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Additional holdings last reported more than 3 years ago are shown separately and excluded from totals.

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	1,548	1,703
Trust	Common Stock	6,162	6,162
SLAT	Common Stock	5,000	5,000

Additional holdings last reported Aug 13, 2003, not confirmed since: 2,700 shares. Not included in any total or percentage on this page.

Daughter 1, Common Stock: 2,700 shares, last reported Aug 13, 2003

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Joseph Goldstein

Director

6.5K

6.7K

no sales

Vesting, gifts, unvested awards and holding lines for Joseph Goldstein

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	6,548	6,703

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Jason Pitofsky

Minor difference of 20 shares. Difference is under 0.5% of holdings.

SVP Controller

4.9K

−2.5K

4.5K

92%

Vesting, gifts, unvested awards and holding lines for Jason Pitofsky

+1Kshares vested or exercised

0gifted (net of own trusts)

−989withheld by the company for taxes

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	4,664	4,272
Spouse	Common Stock	179	179
401(k) Plan	Common Stock	11	31

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
905	$492.00	Dec 9, 2030	$331K
1,978	$644.54	Dec 8, 2031	$421K
3,978	$726.53	Dec 16, 2032	$521K
3,264	$843.79	Dec 8, 2033	$44K
3,236	$771.64	Dec 6, 2034	$277K
2,261	$726.71	Dec 5, 2035	$295K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Reconciliation: minor difference of 20 shares. Difference is under 0.5% of holdings.

Christine Poon

Director

2.4K

−6.5K

5.2K

not meaningful

Vesting, gifts, unvested awards and holding lines for Christine Poon

+9.2Kshares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	2,352	5,219

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Anthony Coles

Director

1.6K

1.7K

no sales

Vesting, gifts, unvested awards and holding lines for Anthony Coles

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	1,559	1,714

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Bonnie Bassler

Director

1.5K

−2.3K

1.7K

not meaningful

Vesting, gifts, unvested awards and holding lines for Bonnie Bassler

+2.3Kshares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	1,548	1,703

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
756	$371.40	Jan 2, 2029	$367K
2,861	$374.12	Jan 2, 2030	$1.4M
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Huda Zoghbi

Director

1.5K

−2.4K

1.7K

not meaningful

Vesting, gifts, unvested awards and holding lines for Huda Zoghbi

+2.4Kshares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	1,548	1,703

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Craig Thompson

Director

620

775

no sales

Vesting, gifts, unvested awards and holding lines for Craig Thompson

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	620	775

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
1,607	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

Kathryn Guarini

Director

448

−800

603

not meaningful

Vesting, gifts, unvested awards and holding lines for Kathryn Guarini

+800shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	448	603

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
508	$888.34	Jan 2, 2034	$0
1,158	$719.37	Jan 2, 2035	$160K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

David Schenkein

Director

448

603

no sales

Vesting, gifts, unvested awards and holding lines for David Schenkein

0shares vested or exercised

0gifted (net of own trusts)

none reportedunvested awards, start → end

Held through	Share class	Oct 8, 2025	Oct 8, 2026
Direct	Common Stock	448	603

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
508	$888.34	Jan 2, 2034	$0
1,958	$719.37	Jan 2, 2035	$270K
1,962	$772.76	Jan 2, 2036	$166K

Estimate: options held × ($857.39 − strike price), using the most recent insider trade price on Form 4 (Sep 3, 2026), not a market close.

17 of 19 insiders fully reconciled: starting holdings plus reported transactions match ending holdings (11 exactly, 6 with a minor or footnoted difference). For 2 we show sales but not holdings; the ! icon on their rows explains why. Percentages cover 13 of 19 officers and directors. Left out: Leonard Schleifer and Daniel Van Plew (holdings couldn't be fully reconciled); Christine Poon, Bonnie Bassler, Huda Zoghbi and Kathryn Guarini (most of their shares vested during the period, so a percentage would mislead). "Still held" compares ending with starting vested shares; a plus sign means the holding grew.

What explains the selling$12.9M of sales by plan status, purpose, seller and month

Officer and director open-market sales: $12.9M across 17,411 shares. Plan status and stated purpose are separate questions, and a sale can have both.

By plan status

Disclosed plan · $8.4M · 65%

35%

The lighter segment is sales with no plan disclosed in the filing ($4.5M), including tax-related sales outside a plan.

No plan disclosed · $4.5M

Sales with no 10b5-1 plan and no tax reference in the filing. $4.3M of it is Christine Poon. No plan disclosed is a statement about the filing, not about why the sale happened. Largest such sale: Christine Poon, Oct 29, 2025

Taxes

425,261 shares ($303M) were withheld by the company for taxes, which isn't a market sale.

Seller	Shares sold	Proceeds	Under a disclosed plan	Share of total	Sales dates
Christine Poon Director	6.5K	$4.3M	0%	33%	Oct 29, 2025 to Oct 29, 2025
Marion McCourt EVP Commercial	2.3K	$2.0M	100%	16%	Sep 2, 2026 to Sep 3, 2026
Huda Zoghbi Director	2.4K	$1.9M	100%	15%	Feb 19, 2026 to Aug 10, 2026
Jason Pitofsky SVP Controller	2.5K	$1.9M	85%	14%	Nov 7, 2025 to Feb 9, 2026
Bonnie Bassler Director	2.3K	$1.8M	100%	14%	Nov 20, 2025 to Jan 7, 2026
Kathryn Guarini Director	800	$660K	100%	5%	Aug 10, 2026 to Sep 2, 2026
Arthur Ryan Director	600	$435K	100%	3%	Feb 9, 2026 to Jul 2, 2026

Sales by month

Month	Sale proceeds	Disclosed plan	To cover taxes	No plan disclosed
Oct 2025	$4.3M	$0	$0	$4.3M
Nov 2025	$851K	$570K	$0	$281K
Dec 2025	$0	$0	$0	$0
Jan 2026	$1.2M	$1.2M	$0	$0
Feb 2026	$2.9M	$2.9M	$0	$0
Mar 2026	$79K	$79K	$0	$0
Apr 2026	$78K	$78K	$0	$0
May 2026	$71K	$71K	$0	$0
Jun 2026	$0	$0	$0	$0
Jul 2026	$130K	$130K	$0	$0
Aug 2026	$960K	$960K	$0	$0
Sep 2026	$2.3M	$2.3M	$0	$0
Oct 2026	$0	$0	$0	$0

Is this normal? Selling year by year5 earlier years to compare with

Less than usual: about one-fifteenth of the 5-year average. 7 insiders sold; the average is 13 a year.

12 months ending	Shares sold	Insiders who sold	Proceeds
Oct 8, 2026 Latest 12 months	17K	7	$12.9M
Oct 8, 2025 1 year earlier	1K	1	$845K
Oct 8, 2024 2 years earlier	332K	16	$324M
Oct 9, 2023 3 years earlier	117K	13	$91.9M
Oct 9, 2022 4 years earlier	238K	18	$158M
Oct 9, 2021 5 years earlier	551K	19	$340M

Open-market sales (Form 4 code S) by people who were officers or directors, in split-adjusted shares. Earlier years include people who have since left. A sale that an outside holder also reports (a family trust, a fund) is counted with outside holders in every year. Shares, not dollars, are compared, so a change in the stock price doesn't look like a change in selling. Years the filings don't fully cover are shown but left out of the average.

Known gaps and uncertainty2 insiders whose holdings couldn't be fully reconciled

Leonard Schleifer: holdings couldn't be fully reconciled (difference of 157,609 shares). Balance changed with no matching transaction and no footnote: +300,000 shares on Dec 9, 2025 (2025 GRAT). Filing, Dec 9, 2025

Daniel Van Plew: holdings couldn't be fully reconciled (difference of -12,347 shares). Balance changed without a matching transaction, and the footnote does not state the amount: -12,376 shares on Dec 5, 2025 (Direct). Filing, Dec 5, 2025

Footnote: "Award of Restricted Stock under the Second Amended and Restated 2014 Long-Term Incentive Plan that vests 50% on December 5, 2027 and 50% on December 5, 2029."

George Yancopoulos: minor difference of 59 shares. Difference is under 0.5% of holdings.

Andrew Murphy: minor difference of 49 shares. Difference is under 0.5% of holdings.

Joseph Larosa: minor difference of 42 shares. Difference is under 0.5% of holdings.

Christopher Fenimore: minor difference of 59 shares. Difference is under 0.5% of holdings.

Marion McCourt: minor difference of 45 shares. Difference is under 0.5% of holdings.

Jason Pitofsky: minor difference of 20 shares. Difference is under 0.5% of holdings.

Inferred rename: "Son" is treated as the same holder as "Spouse/Cust Son", because the old name was never reported again and the new one opened with the same balance (5,000 shares). Old name, new name

Inferred rename: "2023 GRAT" is treated as the same holder as "2025 GRAT", because the old name was never reported again and the new one opened with the same balance (12,376 shares). Old name, new name

Inferred rename: "Trust" is treated as the same holder as "Spouse", because the old name was never reported again and the new one opened with the same balance (179 shares). Old name, new name

External context: we only cite outside events when a documented connection exists. None is shown for this period.

Sources and methodology1,515 filings from SEC EDGAR, and how we read them

All 1,515 Forms 3, 4 and 5 filed for Regeneron Pharmaceuticals (SEC CIK 872589) from Mar 17, 2003 to Sep 3, 2026, retrieved from SEC EDGAR on Oct 8, 2026. Prices are the ones reported in each filing, often weighted averages. 4 filings were left out because Regeneron Pharmaceuticals filed them as an owner of another company's stock. 1 older filing exists only on paper and could not be read.

Holdings. Each holding line (a share class plus an owner, such as a trust or LLC) carries its last reported balance forward. Entities first reported during the period start at zero, so transfers between an insider's own trusts don't count as selling. Lines not reported for three years or more are listed separately and left out of totals.

Sales. A sale counts as under a 10b5-1 plan if its footnote cites one or the filing's Rule 10b5-1 box is checked, and as tax-related if its footnote cites tax obligations or sell-to-cover. Shares withheld by the company for taxes are listed separately. Sales with neither attribute are labeled "no plan disclosed".

Full methodology

Former or inactive filers (20)No filing in 18 months; last reported balances, not in any total

Name	Last filed	Last reported balance
Neil Stahl	Dec 18, 2024	83,225 shares, last reported balance as of Dec 16, 2024
Robert Landry	Feb 6, 2024	23,963 shares, last reported balance as of Feb 2, 2024
Roy Vagelos	Apr 5, 2023	581,413 shares, last reported balance as of Apr 3, 2023
Marc Tessier-Lavigne	Jan 5, 2023	2,434 shares, last reported balance as of Jan 3, 2023
Sanofi	Jun 11, 2020	30,896,271 shares, last reported balance as of Jun 9, 2020
Charles Baker	Jan 3, 2018	9,000 shares, last reported balance as of Sep 29, 2017
Robert Terifay	Dec 13, 2017	26,913 shares, last reported balance as of Aug 10, 2017
Michael Aberman	Jun 23, 2017	16,946 shares, last reported balance as of Jun 22, 2017
Peter Powchik	Dec 19, 2016	32,306 shares, last reported balance as of Dec 16, 2016
Douglas McCorkle	Dec 29, 2015	10,995 shares, last reported balance as of Dec 29, 2015
Alfred Gilman	Aug 7, 2015	8,912 shares, last reported balance as of Aug 6, 2015
Robert Ingram	May 27, 2015	1,500 shares, last reported balance as of May 27, 2015
Murray Goldberg	Dec 18, 2014	70,836 shares, last reported balance as of Dec 16, 2014
Eric Shooter	Feb 13, 2014	24,815 shares, last reported balance as of Feb 12, 2014
William Roberts	Feb 6, 2014	72,278 shares, last reported balance as of Oct 2, 2013
Stuart Kolinski	Jun 7, 2010	20,039 shares, last reported balance as of Jun 3, 2010
Peter Dworkin	Dec 22, 2009	No balance on record
Randall Rupp	Apr 17, 2007	3,983 shares, last reported balance as of Apr 13, 2007
NOVARTIS PHARMA AG	Nov 10, 2005	-7,527,050 shares, last reported balance as of Nov 8, 2005
Hans Guler	Oct 12, 2004	10,530 shares, last reported balance as of Oct 8, 2004

Regeneron Pharmaceuticals insiders sold $12.9M in the past 12 months. How much of their stake is that?

What stands out

Who sold, and how much of their stake

Selling by month

Common questions

Is the Regeneron Pharmaceuticals CEO selling stock?

Why are Regeneron Pharmaceuticals insiders selling?

Are any Regeneron Pharmaceuticals insiders buying?

How much of their stake did Regeneron Pharmaceuticals insiders sell?

The evidence

No plan disclosed · $4.5M

Taxes

Sales by month