NEW YORK ( TheStreet) -- Shares of Warren Buffett's Berkshire Hathaway (BRKA-A) are down over 12% thus far in 2015, compared with a 3% drop in the S&P 500.

Still, Daniel Beckerman, president of financial-planning firm Beckerman Institutional, said investors shouldn't turn a blind eye to the Oracle of Omaha  -- or his protégés Todd Combs and Ted Weschler.

"If you look at their track records from when they ran their hedge funds, they really blew away the stock-market indexes, so I am positive on their future," Beckerman said, adding that Berkshire is a smart domestic play in a jittery global economy.

Beckerman is also bullish on shares of Zillow (Z), which have been flat since the company split its stock three for one this summer. He said the online real-estate company is integrating its Trulia acquisition and is making headway with millennials now searching for starter homes.

"They were smart enough to buy out their most viable competitor there, and even after that acquisition, they only control about 30% of their market," Beckerman said. "It's a highly fragmented industry, but because of their superior brand recognition, they are growing their piece of the pie."

Beckerman said shares of Greenbrier Cos. (GBX) have fallen over 28% year to date because of "perceived exposure to the energy industry". However, he sees the railcar maker turning its fortunes around in coming months because it's highly profitable and trades at a price-to-earnings multiple of less than eight times its trailing 12 months earnings.

"They have this beautiful hidden asset, which I love, of a backlog of over 40,000 orders worth in the billions of dollars, so this is a stock that can double and still be reasonably priced," Beckerman said.

Finally, Beckerman is a fan of Spirit Airlines (SAVE), which is down 31% year to date, saying that the company is highly profitable, especially because of the drop in oil prices and trades at a dirt-cheap P-E multiple of 10 times next year's earnings estimate.