Apple worth $655B on back of iPhone 5 18 (UPI) -- Stock of U.S. technology giant Apple hit a high above $700 Tuesday, as the world's most valuable company ever adds to its value. With the iPhone 5 on the market -- and with the company saying it sold more than 2 million of the smart phones on its first day of pre-orders -- Apple is now valued at $655 billion, the Los Angeles Times reported. Apple became the most valuable company ever, when its valuation reached $623.1 billion on April 20. Its stock was worth $664.74 per share at that point. The most valuable company previously was Microsoft Corp., which was worth $620.6 billion in 1999, although was worth only $257.6 billion as of August. More recently, Apple became No. 1 when it surpassed Exxon Mobil in market capitalization in August 2011. Currently Exxon Mobil is worth $406 billion. On Tuesday, the price for Apple stock hit $701.44 in midmorning trading.