NetJets, the corporate aircraft unit of Warren Buffett's Berkshire Hathaway, said on Thursday it bought Marquis Jet, which offers cards that let business travelers use the NetJets fleet.

Terms were not disclosed. Founded in 2001, Marquis provides cards that offer access to NetJets planes 25 hours at a time.

NetJets is run by David Sokol, who also chairs Berkshire's MidAmerican Energy unit and is widely considered a top candidate to eventually succeed Buffett, 80, as Berkshire's chief executive.

Speaking on CNBC television, Sokol said Buffett is for now "in great shape" and "not going anywhere." Sokol also praised Todd Combs, named on Oct. 26 to run some Berkshire investments, saying the hedge fund manager should do a "great job."

Buffett installed Sokol at NetJets in August 2009 to slash capacity and a $1.9 billion debt load after difficult economic conditions curtailed business travel.

NetJets swung to a profit in the April-to-June quarter, and Berkshire has said it expects the unit to remain profitable. Last month, Brazil's Embraer agreed to sell as many as 125 planes to NetJets.

Based in Omaha, Nebraska, Berkshire is expected to report third-quarter results after U.S. markets close on Friday. It has roughly 80 operating units and tens of billions of dollars of common stock investments.