Fidelity Will Close Two Funds to New Investors

Fidelity Investments said Thursday that it would close two large and recently popular mutual funds to new investors, two weeks after closing its biggest fund, the $65-billion Contrafund.

Some observers characterized the closures as preemptive steps to prevent sagging returns that can result when a fund gets so big that it becomes unmanageable and risks straying from its investment objective.

Boston-based Fidelity, the nation’s largest mutual fund manager, said its Growth Company fund and Mid-Cap Stock fund have both recently attracted a surge of new investor money amid healthy returns. The funds will be closed to new investors after April 28, although existing shareholders will still be able to put in more money.

The Growth Company fund, which invests primarily in the stocks of companies seen as having above-average growth potential, is Fidelity’s sixth-largest fund, with $30 billion in net assets as of March 31. It posted a first-quarter return of 6.9%.

The $11.9-billion Mid-Cap Stock fund is 17th-largest among Fidelity’s more than 300 funds. The fund, which focuses on shares of medium-sized companies, returned 13.4% in the first quarter.