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In fact, his mid-cap fund, Nicholas Fund, is beating the Street. It has seen gains of more than 12 percent in the last year, beating its benchmark, the Russell Mid-Cap Growth, which is up about 9 percent.
Nicholas said the mid-cap sector brings the security of companies big enough to complete without the risks of small-cap names.
"Those companies tend to be able to grow but also not be as volatile, if you will, as some of the small-cap stocks," he said.
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The fund's top holdings include health-care names. While Nicholas likes the sector, he said he's more of a stock picker.
He likes Gilead Sciences for its great cash flow and ability to reinvent itself continuously. "They have great momentum right now, and we think that will continue."
Valeant Pharmaceuticals is another name Nicholas likes. He called it a well-managed company that has great opportunities to expand both organically and through acquisitions.
Disclosure: Nicholas owns Gilead Sciences and Valeant Pharmaceuticals.