Propelled by yields that have been at 18-year highs for the past nine months, high-yield bond funds rose 23% in the first half of the year.

But managers of the funds don’t think those returns can be sustained. “There’s been a huge rally in high yield, with everyone repricing out the depression scenario,” said Fred Hoff, manager of the Fidelity High Income Fund, which rose 26% in the first half of the year. “I don’t think we’re going to double that return this year, though [it] should be very nice,” he told The Wall Street Journal.

Last year, high-yield funds experienced outflows every month, but through May, they took in inflows every month, including $4 billion in April and $3.3 billion in May.

But those investors might be too late, fund managers say. “Anybody with outsized expectations is likely to be disappointed,” said Jeff Tjornehoj, a senior research analyst at Lipper. “There have been some fantastic returns, but those were historical high marks. It’s unlikely we’ll see those again.” As the economic recovery kicks in, he expects those yields to come down.

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