Amazon has become the second company on the U.S. stock market to surpass a trillion dollars in value after Apple.<br /> The online retail giant enjoyed the milestone briefly on Tuesday before slipping back.<br />However, market watchers are confident it won't take long for the firm's stock market valuation to eclipse that of Apple.<br />The iPhone maker took 38 years as a public company to reach the 13-digit milestone, while Amazon got there in 21. <br />As well as its online retail servive, Amazon's video streaming and cloud computing services for businesses have helped boost its profits. <br />
