Does Primecap own RMBS stock?

Yes. As of its Q2 2026 13F, Primecap holds 47,500 shares of RMBS (Rambus), worth $6.3M.

How many shares of RMBS does Primecap own?

As of its Q2 2026 13F, Primecap holds 47,500 shares of RMBS (Rambus).

As of its Q2 2026 13F, Primecap's RMBS position is worth $6.3M.

Primecap already held RMBS in its Q4 2018 13F, the earliest on record, and has listed it in 31 quarterly 13F filings.

31 quarters

Position history for PRIMECAP Management Co.'s holdings in Rambus, Inc.

Current Value

$6.3M

Current Shares

47,500

Total Value Change

-$3.3M

Total Shares Change

-1.2M

Quarter-by-Quarter History

Quarter	Action	Shares	Change	Value	Weight	Price
2026-Q2 Latest	Unchanged	47,500	0.0%	$6.3M	0.0%	$132.74
2026-Q1	Unchanged	47,500	0.0%	$4.1M	0.0%	$86.03
2025-Q4	Decreased	47,500	-19.5%	$4.4M	0.0%	$91.89
2025-Q3	Decreased	59,000	-5.3%	$6.1M	0.0%	$104.20
2025-Q2	Decreased	62,300	-14.5%	$4M	0.0%	$64.02
2025-Q1	Decreased	72,900	-11.6%	$3.8M	0.0%	$51.78
2024-Q4	Decreased	82,500	-12.7%	$4.4M	0.0%	$52.86
2024-Q3	Decreased	94,500	-8.8%	$4M	0.0%	$42.22
2024-Q2	Decreased	103,600	-19.2%	$6.1M	0.0%	$58.76
2024-Q1	Decreased	128,200	-5.0%	$7.9M	0.0%	$61.81
2023-Q4	Decreased	134,963	-18.8%	$9.2M	0.0%	$68.25
2023-Q3	Decreased	166,163	-14.9%	$9.3M	0.0%	$55.79
2023-Q2	Decreased	195,363	-18.1%	$12.5M	0.0%	$64.17
2023-Q1	Unchanged	238,663	0.0%	$12.2M	0.0%	$51.26
2022-Q4	Decreased	238,663	-2.8%	$8.5M	0.0%	$35.82
2022-Q3	Decreased	245,563	-3.0%	$6.2M	0.0%	$25.42
2022-Q2	Decreased	253,163	-3.8%	$5.4M	0.0%	$21.49
2022-Q1	Decreased	263,163	-1.8%	$8.4M	0.0%	$31.89
2021-Q4	Decreased	267,963	-6.4%	$7.9M	0.0%	$29.39
2021-Q3	Decreased	286,263	-3.1%	$6.4M	0.0%	$22.20
2021-Q2	Decreased	295,289	-7.2%	$7M	0.0%	$23.71
2021-Q1	Decreased	318,048	-64.4%	$6.2M	0.0%	$19.44
2020-Q4	Decreased	892,445	-0.2%	$15.6M	0.0%	$17.46
2020-Q3	Unchanged	893,945	0.0%	$12.2M	0.0%	$13.69
2020-Q2	Decreased	893,945	-0.5%	$13.6M	0.0%	$15.20
2020-Q1	Decreased	897,945	-3.0%	$10M	0.0%	$11.10
2019-Q4	Decreased	925,345	-1.1%	$12.7M	0.0%	$13.78
2019-Q3	Decreased	936,045	-24.7%	$12.3M	0.0%	$13.13
2019-Q2	Decreased	1.2M	-0.4%	$15M	0.0%	$12.04
2019-Q1	Decreased	1.2M	-0.8%	$13M	0.0%	$10.45
2018-Q4	First report	1.3M	-	$9.7M	0.0%	$7.67

Other major holders of RMBS: BlackRock, Inc., FMR LLC