By Hamza HednawiCAIRO -- Egypt's benchmark stock index on Sunday plunged by more than 9.5% in the first trading session since the country's Islamist president issued decrees to assume sweeping new powers, while police in central Cairo fired tear gas at protesters who accuse the Egyptian leader of a blatant power grab. President Mohammed Morsi edicts, which were announced on Thursday, place him above oversight of any kind, including that of the courts. The move has thrown Egypt's already troubled transition to democracy into further turmoil, sparking angry protests across the country to demand the decrees be immediately rescinded. The judiciary, which was the main target of Morsi's edicts, has pushed back. Judges and prosecutors stayed away from several courts in Cairo and the southern cities of Assiut and Luxor to protest the presidential decrees. > > Bull or Bear? Vote in Our Poll With the opening bell of the country's stock market on Sunday, the first day of the workweek in Egypt, the turmoil spread from the country's bitter politics to its already ailing economy. The Egyptian Exchange's EGX30 index dropped 9.59% points, making the losses among the biggest since the turbulent days and weeks immediately after the ouster in a popular uprising of authoritarian leader Hosni Mubarak last year. Morsi, who narrowly won the presidency in June, says his measures were designed to "protect the revolution," but they triggered an uproar among non-Islamist political groups now vowing to press on with street protests to force him to back down. Prominent Egyptian democracy advocate Mohammed ElBaradei warned Saturday of increasing turmoil that could potentially lead to the military stepping in unless Morsi rescinds his new powers, as the country's long fragmented opposition sought to unite and rally new protests. Egypt's liberal and secular forces -- long divided, weakened and uncertain amid the rise of Islamist parties to power -- are seeking to rally themselves in response to the decrees. On Sunday, protesters clashed with police in Cairo's Tahrir square, birthplace of the uprising that toppled Mubarak, and in the side streets and avenues leading off the plaza. The Interior Ministry, which is in charge of the police, said a total of 267 protesters have been arrested and 164 policemen injured since the protest began a week ago, initially to mark the anniversary of street protests a year ago against the nation's then-military rulers. Forty-two protesters were killed in those demonstrations.