By Dan Weil Amazon shares have risen since its split announcement, and if history is any guide, more appreciation may be coming. Amazon (AMZN) – Get Amazon.com, Inc. Report on March 9 declared a 20-for-1 stock split, providing a highlight amid the equity market’s turmoil. Amazon’s stock has risen since the move, including a 0.8% gain Friday. And if history is any guide, more appreciation may be coming. Since 1980, S&P 500 companies that have declared stock splits have significantly outperformed the index for three, six and 12 months after the initial announcement, according to Bank of America …