Saudi Arabia's stock market rose sharply in early trade on Thursday on hopes for a global agreement to prop up oil prices, while Egypt's bourse was firm. The Saudi index gained 1.5 percent in the opening minutes, heading for its fourth straight day of gains, as the biggest petrochemical maker, Saudi Basic Industries, climbed 2.9 percent. The market largely ig**red news overnight that Standard & Poor's had cut its credit rating of Saudi Arabia by two **tches to A- from A+, citing the impact on state finances of low oil prices.