Question 1

Does PRIMECAP Management own RMBS stock?

Accepted Answer

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

Question 2

How many shares of RMBS does PRIMECAP Management own?

Accepted Answer

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

Question 3

What is PRIMECAP Management's RMBS position worth?

Accepted Answer

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

Question 4

When did PRIMECAP Management first buy RMBS?

Accepted Answer

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

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