American Funds' Growth Fund of America, the nation's biggest fund and, since 2003, its best-selling, should close, analysts told Bloomberg.

With $142 billion in assets, the fund alone would rank as the eighth-largest fund company in the nation. In the past three years, it has nearly doubled in size, attracting $63 billion in net new assets, which is not surprising, given its annual average returns of 17% in that period.

That's an average of 3.8 percentage points ahead of the S&P 500.

However, Paul Herbert, an analyst with Morningstar, does not believe such returns are sustainable for a fund that size, and Burton Greenwald, a fund consultant, concurs. "It's very hard to see how a fund of that magnitude is going to outperform a large-cap index," Greenwald said.

But Capital Group, the fund's investment advisor, has no plans to close Growth Fund of America or any of the company's other 28 funds, spokesman Chuck Freadhoff said.

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