Amazon stock surged to more than $1,000 for the first time on Tuesday, marking a milestone for the dominant e-commerce retailer and leaving its closest competitors still trying to figure out a path to closing the gap. Amazon's shares hovered near $997 in late mid-afternoon trading after reaching $1001.20 earlier in the day, an all-time-high for the stock. Friday's closing price was $995.78. The key to Amazon's dominance has been growth in its Prime membership, which has doubled to more than 80 million members in the past two years.