The government has picked four investment banks to advise it on the planned sale of a stake in state-controlled natural-gas monopoly DEPA, sources said yesterday. «Greece has hired Alpha Bank, Deutsche Bank, Rothschild and UBS,» said an Economy and Finance Ministry official who declined to be named, according to Reuters. The banks are likely to spend a couple of months working with DEPA and the government before contact begins in earnest with potential buyers, perhaps in September, the source said. Greece owns 65 percent of DEPA. In March, it dropped plans to float the company and said it would instead focus on finding a strategic investor.