Saudi Arabian shares gained the most in a week, led by petrochemical companies and banks, after US Federal Reserve Chairman Ben Bernanke said he is prepared to do more to stimulate US growth. Saudi Basic Industries Corp., the world\'s largest petrochemicals maker, climbed the most in a week. Almarai Co., the kingdom\'s biggest food producer, jumped 4.7 per cent after saying a new infant formula plant will start production in May. Samba Financial Group advanced the most in more than a month. The Tadawul All Share Index rose 0.7 per cent, the most since April 21, to 7,594.57 in Riyadh. The 152-member index has increased 18 per cent this year. The forecasts by the US Federal Reserve \"for growth and unemployment may have a positive impact on the Saudi market, particularly the petrochemical sector,\" Turki Fadaak, head of research at Riyadh-based Albilad Investment Co., said. The Fed on April 25 upgraded its estimates for growth and unemployment this year while repeating its view that borrowing costs are likely to remain \"exceptionally low\" at least through late 2014. Oil for June delivery climbed 0.4 per cent to $104.93 a barrel yesterday in New York, the highest settlement since April 2. Futures advanced 1.8 per cent this week. \"Market activity reflects the gathering anticipation for further stimulus by the Fed in the US,\" Asim Bukhtiar, head of research at Riyad Capital, said in response to emailed questions. \"Crude gained over the weekend, which is lifting petrochemicals and the broader market.\" Saudi Basic advanced 0.7 per cent to 103.5 riyals. Almarai rose to 67.25 riyals. Samba, the country\'s second largest bank by market value, gained 3 per cent to 52 riyals. Saudi Arabia\'s stock exchange is the only Gulf Arab bourse operating on Saturdays.