Los Angeles Apple is now worth over $500 billion (Dh1.83 trillion) — and counting. The company\'s market value passed the rarefied half-trillion-dollar mark in trading on Wednesday, joining just a handful of firms to have reached those heights, though none managed to stay there. For much of last year, Apple was running neck and neck with ExxonMobil for the title of most valuable firm. But over the last month Apple has catapulted nearly $100 billion past Exxon, which is now worth about $407 billion. Market value is a measure of the total combined value of all of its outstanding shares of stock. Apple\'s stock jumped $7.03, or 1.3 per cent, to $542.44 on Wednesday, putting the company\'s value at $506 billion when regular trading ended. The lift came a day after Apple sent invitations to the media for an event next Wednesday in which it is expected to release its third-generation iPad. The financial equivalent of scaling Mt Everest, only a few companies have reached the $500-billion mark, many of them during the dot-com boom early last decade. But the footing at that altitude is tricky, and companies that reached the summit soon slid down again. Exxon stayed at about $500 billion for two brief periods toward the end of 2007, according to an analysis by AP. Microsoft, Apple\'s longtime computing rival, passed the $500-billion line in 1999 and then again in 2000, and even reached $600 billion for one day. From gulfnews