Warren Buffett’s Berkshire Hathaway has taken a 5.4% stake in tech sector giant IBM, and he remains upbeat on equities over the long haul, though he says a “depression” in the housing sector is holding back the economy.

Buffett tells CNBC that IBM has done a very good job of publicly laying out goals and accomplishing them. He also says that the tech giant has “a very good business” and “this terrific reverence for shareholders”.

Buffett also says that housing continues to be the big drag on the U.S. economy. Outside of the housing sector, he says, businesses across all sorts of industries — including those owned by Berkshire — are doing very well. “You have a huge segment of the American economy that’s doing really quite well,” he says. “[But] what is getting killed and what is in a — not in a recession but in a depression — is anything connected with residential construction. And that includes things like our carpet business, our insulation business, our brick business. Those businesses are in a depression.”

Buffett says that the housing sector and overhang of supply is having more of an impact than many realize on the unemployment rate. When an equilibrium gets reached between housing supply and the number of new households being created, he says the unemployment rate should drop significantly. He thought that would start to happen by the end of this year, but it now seems like it will take longer, he says.

Overall, Buffett remains bullish on the U.S. economy and stocks, as well as other “productive” assets. “I believe in owning productive assets … whether it’s farms, apartment houses or businesses,” he says. “And they’ll do very well over time, and sometimes one class is doing better than another. But if you own any of those things over the next 20 years in the United States, I think you’ll do well.”