Saudi Arabia's benchmark stock index swung between gains and losses on speculation investors are adjusting their holdings ahead of the Kingdom's budget report. Etihad Etisalat Co., the Kingdom's second-largest phone company known as Mobily, dropped 0.5 percent. Saudi Basic Industries Corp., the world's largest petrochemicals maker which accounts for 12 percent of the index, was unchanged. The Tadawul All Share Index dropped 0.1 percent to 6,373.37 at 1:07 p.m., trimming the monthly gain to 4.4 percent. The gauge earlier rose as much as 0.3 percent. “Volumes on the Tadawul are climbing up in the final days of 2011,” said Asim Bukhtiar, an equity analyst at Riyad Capital. “The anticipated budget announcement and year-end positioning are the contributing factors.” Saudi Arabia is set to announce its budget for 2012, said Turki Fadaak, head of research at Albilad Investment Co.