Don't Blame the Market's Drop: Here's Why Roku Stock Suddenly Sank Today

Shares of connected-TV platform company Roku (ROKU -8.76%) were trending down along with the S&P 500 until about 3 p.m. ET when Roku stock suddenly sank. This market move coincides with a report from The Wall Street Journal that says that retail giant Walmart (WMT -0.68%) wants to buy smart TV maker Vizio (VZIO 24.68%).As of 3:40 p.m. ET, Roku stock was down 10%. For its part, Vizio stock was up 27%, whereas Walmart stock was relatively unchanged.Why do Roku investors care?Vizio's business is quite similar ...