Offshore driller Ocean Rig UDW Inc is preparing to explore a sale amid pressure from some of its largest shareholders to review its strategic alternatives, according to three people familiar with the matter. The move will be a key test of Ocean Rig’s value after it emerged from Chapter 15 bankruptcy in September, Reuters reported. Its business has suffered as low oil prices have made offshore drilling less economically attractive and pushed more oil exploration onshore. Ocean Rig has interviewed investment banks in recent weeks to appoint a financial adviser that will help it explore a sale, the sources said this week. There is no certainty that the company will end up agreeing to any deal, said the sources, who asked not to be identified because the matter is confidential. Ocean Rig did not respond to a request for comment. Shares jumped as much as 7 percent on the news, and were up 4.3 percent at $25.90 in morning trading in New York on Wednesday, giving the company a market capitalization of $2.4 billion. Read more.