Saudi Aramco (SE:2222) IPO begins trading on Tadawul Exchange (Saudi Exchange). It replaced Alibaba to top the world IPO record with US$25.6 billion raised. At this level, Aramco would have a market valuation of $1.7 trillion, overtaking Apple Inc as to the most valuable listed firm. The shares spiked 10% Wednesday when they hit the market in the world's biggest-ever IPO. The shares leapt to 35.2 riyals ($9.39) each, up from the IPO price of 32 riyals and at the daily limit of price moves allowed by the Tadawul exchange.