Amazon trounces rivals in battle of the shopping 'bots'

Earlier this year, engineers at Wal-Mart Stores who track rivals' prices online got a rude surprise: the technology they were using to check Amazon.com Inc's data was no small matter. Like most big retailers, Wal-Mart relies on computer programs that scan prices on competitors' websites so it can adjust its listings accordingly. Amazon's mastery of the complex, behind-the-scenes technologies that power modern e-commerce allows it to see what its rivals are doing, but increasingly to keep them in the dark. In the world of e-commerce, retailers update prices with ease, sometimes multiple times a day, helped by algorithms that consider inventory levels, sales forecasts and rivals' pricing data.