Los Angeles biotech billionaire Patrick Soon-Shiong is nearing a deal to buy the Los Angeles Times and the San Diego Union-Tribune from its parent company, Tronc, according to two people familiar with the talks. The nearly $500 million deal would return the Times to local ownership after 18 years and represent a major shift for Tronc, which has long built its strategy around owning newspapers in the country’s largest cities. A deal had not been reached Tuesday afternoon, but both sides were working furiously to complete the transaction and an announcement could come quickly, said those sources, who were not authorized to speak about the negotiations publicly and requested anonymity.