The stock market "doesn't look so cheap," Berkshire Hathaway board member Meryl Witmer told CNBC on Thursday.
"The whole thing about keeping interest rates low, people put money into stocks because they want the yield, or they're gambling, or they're getting nothing on their cash. That really adds to the speculative environment. A bit of a bubble. And at some point you have to pay the piper," said Witmer, who is also general partner at Eagle Capital and part of the Barron's Roundtable.
In a "Squawk Box" interview, she said she doesn't spend a lot of time trying figure out what the Federal Reserve is going to do. But the central bank's decision not to start tapering its $85-billion-a-month bond-buying program did affect some of her investment choices.
"I was a little disappointed because a few stocks were hovering around where I'd like to buy them," she admitted. "I was hoping some negative news would come out and I would get to add a position or two." The Fed's inaction boosted stocks to record highs Wednesday.
As value investors, "our style is really bottoms up. So we're looking at individual companies and try to find a cheap one, find something that's misperceived," said Witmer, who joined the board of Warren Buffett's Berkshire this spring.
"I think one area is refining, and in particular Phillips 66, which is a position of ours," she said.
Besides refining, Phillips 66 also has a chemical business that's a "great niche, very high return on capital," and a "midstream business that moves oil and gas around," she said.
Witmer said she bought shares of Phillips 66 when it was spun out of Conoco Phillips in the spring of 2012. "We've [also] bought some since, even at around these current prices."
Eagle Capital returned 8.78 percent in the June quarter, according to hedge fund track Whale Wisdom. The investment firm had a 28.7 percent performance over the past four quarters.