Saudi Industrial Export Co. ., the best performing stock in Saudi Arabia this year, has escaped recent volatility in the kingdom’s market and is seeking a new contract with state oil-giant Aramco . Increasing demand for sulfur, the company’s main export, boosted results and shares. The stock has soared more than five-fold this year, giving it a market value of 1 billion riyals ($280 million). Saudi Arabia’s benchmark stock index has gained 6.7 percent in the period.