Fidelity will close too more funds in an admissions that some funds are becoming too large to navigate. However, the mere fact that Fidelity leaves two weeks for people to come in indicates the reluctance of management to stop milking these cash cows.

Fidelity Investments will close two more popular mutual funds to new investors at the end of the month, a move that some say signifies a more aggressive Fidelity strategy to protect the performance of its top investment offerings.

The mutual-fund titan based here said it will close the $29.9 billion Fidelity Growth Company Fund and $11.9 billion Fidelity Mid-Cap Stock Fund to newcomers after April 28. The move follows Fidelity's decision to close its biggest fund, and star attraction, the $65.2 billion Fidelity Contrafund, and the $6 billion Fidelity Advisor New Insights Fund, to new investors, also after April 28. (All four closings are as of 4 p.m. EDT on that date.)

All four funds, however, will still accept investments from new investors via retirement plans, such as 401(k)s that already have the funds as an established option on their menu of investment choices. That makes Fidelity's move only a partial choke-off of new investment, but it still represents a choice to forgo some growth in favor of keeping the funds at a more manageable size.