Vanguard Group, one of the biggest mutual-fund managers in the world, said Friday it’s taking steps to limit the growth of its Primecap Core Fund and two related fund, including not accepting new accounts from most clients and limiting additional purchases by shareholders. 

“We are taking preemptive steps to limit the growth of PRIMECAP Core Fund and its sister funds, with the goal of enabling the team at PRIMECAP Management to continue to implement their investment strategy in an effective manner,” Vanguard CEO Bill McNabb said in a press release.

The Primecap Core Fund will no longer accept new accounts from most retail clients, and additional purchases by existing shareholders will be limited to $25,000 a year. The fund is closed to financial-advisor and institutional clients, but the company said the fund remains open without limits to participants in defined-contribution plans and some others. The fund had $3.4 billion in assets as of June 30, and an expense ratio of 0.55% as of Jan. 9.

Top holdings in the Primecap Core Fund are Eli Lilly (LLY), Amgen (AMGN), Novartis (NVS), Roche Holding (RHHVF) and Oracle (ORCL).

Vanguard Primecap Fund and Vanguard Capital Opportunity Fund also now have $25,000 annual limits on the purchase of new shares, Vanguard said. Both of those funds were already closed to new investors.

Vanguard Primecap Fund had $23.8 billion in assets as of June 30, and an expense ratio of 0.50% as of Jan. 28. Its top holdings as of June 30 were Eli Lilly and Amgen.

The Capital Opportunity Fund had $6.7 billion in assets as of June 30, and an expense ratio of 0.52% as of Jan. 28. Its top holdings as of June 30 were Research In Motion (RIMM) and Monsanto (MON).