'Death by Amazon': 20 once thriving companies that find themselves in the e-commerce giant's crosshairs

Investors are familiar with the Amazon effect by now.  The e-commerce juggernaut announces that it is preparing to enter into an industry — be it medication, brick-and-mortar grocery, entertainment, or others — and the stocks of companies in the new target market fall as jittery investors are struck with the fear that irreversible disruption is coming.