The stock has already trounced the S&P 500 since its IPO. Will it continue?Advertising is a pillar of the economy. Ad money is slowly shifting from old-fashioned mediums like print, radio, and broadcast television to digital ones, like the internet and streaming. This trend positions The Trade Desk (TTD 2.49%) as a big winner over the coming decades. The stock has already outperformed the market since going public, but there's plenty more upside ahead.The Trade Desk is worth nearly $42 billion today, so it' ...