Johannes Jacobus Oosthuizen

CIK 1916310 · View on SEC EDGAR ↗

Insider

First SEC filing: March 10, 2022 · Latest: May 7, 2026

On this page

Insider at Companies where this person is a reporting insider.
Insider transactions Every share this person bought or sold, from Form 4 filings.
Derivatives Options and other derivative holdings reported by this person.
Initial holdings The stakes this person held when they first started reporting.

Insider at

MRK selling Feb. 6, 2026

Insider transactions

0 buys (P) 1 sells (S) Net: $-1,828,050 + 55 non-open-market transactions below last 12 months, based on the transactions shown below

Price change vs current quote, split-adjusted for corporate actions since the filing — not benchmarked, not annualized, not size-weighted

55 other filings hidden

Date	Ticker	Code	Shares	Price	Value	Owned after	Δ own	A/D	vs now
May 5, 2026	MRK	A	31,044	—	—	31,044 Direct	—	Acquired	(price as of 2026-08-21)
May 5, 2026	MRK	A	10,605	—	—	10,605 Direct	—	Acquired	(price as of 2026-08-21)
April 29, 2026	MRK	M	1,377	—	—	2,755 Direct	-33.33%	Disposed	(price as of 2026-08-21)
April 29, 2026	MRK	F	679	$110.03	$74,710	21,895 Direct	-3.01%	Disposed	37.8% (price as of 2026-08-21)
April 29, 2026	MRK	M	1,377	$110.03	$151,511	22,574 Direct	+6.50%	Acquired	37.8% (price as of 2026-08-21)
Feb. 6, 2026	MRK	S	15,000	$121.87	$1,828,050	21,197 Direct	-41.44%	Disposed	24.4% (price as of 2026-08-21)
Jan. 26, 2026	MRK	A	5,026	$107.40	$539,792	36,197 Direct	+16.12%	Acquired	41.2% (price as of 2026-08-21)
April 29, 2025	MRK	A	18,807	—	—	18,807 Direct	—	Acquired	(price as of 2026-08-21)
April 29, 2025	MRK	A	4,132	—	—	4,132 Direct	—	Acquired	(price as of 2026-08-21)
Feb. 19, 2025	MRK	S	8,500	$84.09	$714,765	30,705 Direct	-21.68%	Disposed	80.3% (price as of 2026-08-21)
Feb. 8, 2025	MRK	M	13,002	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
Feb. 8, 2025	MRK	F	6,404	$87.28	$558,941	39,205 Direct	-14.04%	Disposed	73.8% (price as of 2026-08-21)
Feb. 8, 2025	MRK	M	13,002	$87.28	$1,134,815	45,609 Direct	+39.87%	Acquired	73.8% (price as of 2026-08-21)
Jan. 27, 2025	MRK	A	8,664	$97.94	$848,552	32,607 Direct	+36.19%	Acquired	54.8% (price as of 2026-08-21)
May 4, 2024	MRK	M	912	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
May 4, 2024	MRK	F	450	$127.51	$57,380	23,821 Direct	-1.85%	Disposed	18.9% (price as of 2026-08-21)
May 4, 2024	MRK	M	912	$127.51	$116,289	24,271 Direct	+3.90%	Acquired	18.9% (price as of 2026-08-21)
April 30, 2024	MRK	A	20,508	—	—	20,508 Direct	—	Acquired	(price as of 2026-08-21)
Feb. 2, 2024	MRK	M	6,773	$75.36	$510,413	28,122 Direct	+31.73%	Acquired	101.2% (price as of 2026-08-21)
Feb. 2, 2024	MRK	M	7,045	$73.73	$519,428	35,167 Direct	+25.05%	Acquired	105.7% (price as of 2026-08-21)
Feb. 2, 2024	MRK	M	7,045	—	—	7,049 Direct	-49.99%	Disposed	(price as of 2026-08-21)
Feb. 2, 2024	MRK	M	7,119	—	—	14,240 Direct	-33.33%	Disposed	(price as of 2026-08-21)
Feb. 2, 2024	MRK	M	6,773	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
Feb. 2, 2024	MRK	S	18,959	$127.18	$2,411,206	23,327 Direct	-44.84%	Disposed	19.2% (price as of 2026-08-21)
Feb. 2, 2024	MRK	M	7,119	$87.10	$620,065	42,286 Direct	+20.24%	Acquired	74.1% (price as of 2026-08-21)
Jan. 22, 2024	MRK	A	3,133	$119.43	$374,174	21,349 Direct	+17.20%	Acquired	27.0% (price as of 2026-08-21)
Nov. 9, 2023	MRK	S	2,081	$102.38	$213,053	18,191 Direct	-10.27%	Disposed	48.1% (price as of 2026-08-21)
Oct. 30, 2023	MRK	M	915	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
Oct. 30, 2023	MRK	F	451	$102.82	$46,372	20,272 Direct	-2.18%	Disposed	47.5% (price as of 2026-08-21)
Oct. 30, 2023	MRK	M	915	$102.82	$94,080	20,723 Direct	+4.62%	Acquired	47.5% (price as of 2026-08-21)
May 4, 2023	MRK	M	907	—	—	912 Direct	-49.86%	Disposed	(price as of 2026-08-21)
May 4, 2023	MRK	F	447	$118.22	$52,844	19,760 Direct	-2.21%	Disposed	28.3% (price as of 2026-08-21)
May 4, 2023	MRK	M	907	$118.22	$107,226	20,207 Direct	+4.70%	Acquired	28.3% (price as of 2026-08-21)
May 2, 2023	MRK	A	20,747	—	—	20,747 Direct	—	Acquired	(price as of 2026-08-21)
May 1, 2023	MRK	M	866	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
May 1, 2023	MRK	F	427	$115.47	$49,306	19,300 Direct	-2.16%	Disposed	31.3% (price as of 2026-08-21)
May 1, 2023	MRK	M	866	$115.47	$99,997	19,727 Direct	+4.59%	Acquired	31.3% (price as of 2026-08-21)
Jan. 23, 2023	MRK	A	2,091	$109.88	$229,759	18,822 Direct	+12.50%	Acquired	38.0% (price as of 2026-08-21)
Nov. 9, 2022	MRK	S	1,795	$103.21	$185,262	16,731 Direct	-9.69%	Disposed	46.9% (price as of 2026-08-21)
Nov. 7, 2022	MRK	M	7,045	—	—	14,094 Direct	-33.33%	Disposed	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	13,540	—	—	6,773 Direct	-66.66%	Disposed	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	17,455	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	14,703	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
Nov. 7, 2022	MRK	S	45,561	$99.47	$4,531,953	18,526 Direct	-71.09%	Disposed	52.5% (price as of 2026-08-21)
Nov. 7, 2022	MRK	M	7,045	—	—	64,087 Direct	+12.35%	Acquired	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	13,540	—	—	57,042 Direct	+31.13%	Acquired	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	17,455	—	—	43,502 Direct	+67.01%	Acquired	(price as of 2026-08-21)
Nov. 7, 2022	MRK	M	14,703	—	—	26,047 Direct	+129.61%	Acquired	(price as of 2026-08-21)
Oct. 30, 2022	MRK	M	913	—	—	915 Direct	-49.95%	Disposed	(price as of 2026-08-21)
Oct. 30, 2022	MRK	F	450	$100.77	$45,346	11,344 Direct	-3.82%	Disposed	50.5% (price as of 2026-08-21)
Oct. 30, 2022	MRK	M	913	$100.77	$92,003	11,794 Direct	+8.39%	Acquired	50.5% (price as of 2026-08-21)
Oct. 28, 2022	MRK	S	3,633	$100.21	$364,063	10,881 Direct	-25.03%	Disposed	51.3% (price as of 2026-08-21)
May 4, 2022	MRK	M	907	$87.10	$79,000	14,961 Direct	+6.45%	Acquired	74.1% (price as of 2026-08-21)
May 4, 2022	MRK	F	447	$87.10	$38,934	14,514 Direct	-2.99%	Disposed	74.1% (price as of 2026-08-21)
May 4, 2022	MRK	M	907	—	—	1,819 Direct	-33.27%	Disposed	(price as of 2026-08-21)
May 3, 2022	MRK	A	21,359	—	—	21,359 Direct	—	Acquired	(price as of 2026-08-21)
May 3, 2022	MRK	M	773	—	—	0 Direct	-100.00%	Disposed	(price as of 2026-08-21)
May 3, 2022	MRK	F	381	$87.65	$33,395	14,054 Direct	-2.64%	Disposed	73.0% (price as of 2026-08-21)
May 3, 2022	MRK	M	773	$87.65	$67,753	14,435 Direct	+5.66%	Acquired	73.0% (price as of 2026-08-21)
May 1, 2022	MRK	M	866	—	—	866 Direct	-50.00%	Disposed	(price as of 2026-08-21)
May 1, 2022	MRK	F	427	$88.69	$37,871	13,662 Direct	-3.03%	Disposed	71.0% (price as of 2026-08-21)
May 1, 2022	MRK	M	866	$88.69	$76,806	14,089 Direct	+6.55%	Acquired	71.0% (price as of 2026-08-21)

P = Open-market purchase · S = Sale · A = Grant/award · M = Option exercise · G = Gift · F = Tax withholding

Insider transactions are not a recommendation; sales are often driven by liquidity or tax reasons.

Derivative holdings (Form 4 Table II)

Options, RSUs and convertible securities reported on Form 4 Table II.

Date	Ticker	Security	Underlying	Exercise price	Expiration	Shares	A/D
May 5, 2026	MRK	Stock Option (Right to Buy)	Common Stock (31,044)	$113.15	May 4, 2036	31,044	Acquired
May 5, 2026	MRK	Restricted Stock Unit	Common Stock (10,605)	—	May 5, 2029	10,605	Acquired
April 29, 2026	MRK	Restricted Stock Unit	Common Stock (1,377)	—	April 29, 2028	1,377	Disposed
April 29, 2025	MRK	Stock Option (Right to Buy)	Common Stock (18,807)	$84.71	April 28, 2035	18,807	Acquired
April 29, 2025	MRK	Restricted Stock Unit	Common Stock (4,132)	—	April 29, 2028	4,132	Acquired
Feb. 8, 2025	MRK	Restricted Stock Unit	Common Stock (13,002)	—	Feb. 8, 2025	13,002	Disposed
May 4, 2024	MRK	Restricted Stock Unit	Common Stock (912)	—	May 4, 2024	912	Disposed
April 30, 2024	MRK	Stock Option (Right to Buy)	Common Stock (20,508)	$129.22	April 29, 2034	20,508	Acquired
Feb. 2, 2024	MRK	Stock Option (Right to Buy)	Common Stock (7,045)	$73.73	May 3, 2031	7,045	Disposed
Feb. 2, 2024	MRK	Stock Option (Right to Buy)	Common Stock (7,119)	$87.10	May 2, 2032	7,119	Disposed
Feb. 2, 2024	MRK	Stock Option (Right to Buy)	Common Stock (6,773)	$75.36	April 30, 2030	6,773	Disposed
Oct. 30, 2023	MRK	Restricted Stock Unit	Common Stock (915)	—	Oct. 30, 2023	915	Disposed
May 4, 2023	MRK	Restricted Stock Unit	Common Stock (907)	—	May 4, 2024	907	Disposed
May 2, 2023	MRK	Stock Option (Right to Buy)	Common Stock (20,747)	$117.89	May 1, 2033	20,747	Acquired
May 1, 2023	MRK	Restricted Stock Unit	Common Stock (866)	—	May 1, 2023	866	Disposed
Nov. 7, 2022	MRK	Stock Option (Right to Buy)	Common Stock (7,045)	$73.73	May 3, 2031	7,045	Disposed
Nov. 7, 2022	MRK	Stock Option (Right to Buy)	Common Stock (13,540)	$75.36	April 30, 2030	13,540	Disposed
Nov. 7, 2022	MRK	Stock Option (Right to Buy)	Common Stock (17,455)	$77.62	May 2, 2029	17,455	Disposed
Nov. 7, 2022	MRK	Stock Option (Right to Buy)	Common Stock (14,703)	$62.07	May 4, 2027	14,703	Disposed
Oct. 30, 2022	MRK	Restricted Stock Unit	Common Stock (913)	—	Oct. 30, 2023	913	Disposed
May 4, 2022	MRK	Restricted Stock Unit	Common Stock (907)	—	May 4, 2024	907	Disposed
May 3, 2022	MRK	Stock Option (Right to Buy)	Common Stock (21,359)	$87.10	May 2, 2032	21,359	Acquired
May 3, 2022	MRK	Restricted Stock Unit	Common Stock (773)	—	May 3, 2022	773	Disposed
May 1, 2022	MRK	Restricted Stock Unit	Common Stock (866)	—	May 1, 2023	866	Disposed

Exercise/conversion price is blank when not applicable (e.g. RSUs).

Initial ownership (Form 3) 10 holdings

Securities held when first becoming an insider, per SEC Form 3.

Date	Ticker	Security	Shares	Ownership
March 10, 2022	MRK	Common Stock	13,222	Direct
March 10, 2022	MRK	Restricted Stock Unit→ Common Stock (773)	773	Direct
March 10, 2022	MRK	Restricted Stock Unit→ Common Stock (1,732)	1,732	Direct
March 10, 2022	MRK	Restricted Stock Unit→ Common Stock (1,828)	1,828	Direct
March 10, 2022	MRK	Restricted Stock Unit→ Common Stock (2,726)	2,726	Direct
March 10, 2022	MRK	Restricted Stock Unit→ Common Stock (13,002)	13,002	Direct
March 10, 2022	MRK	Stock Option (Right to Buy)→ Common Stock (14,703)	14,703	Direct
March 10, 2022	MRK	Stock Option (Right to Buy)→ Common Stock (17,455)	17,455	Direct
March 10, 2022	MRK	Stock Option (Right to Buy)→ Common Stock (20,313)	20,313	Direct
March 10, 2022	MRK	Stock Option (Right to Buy)→ Common Stock (21,139)	21,139	Direct