Netflix Inc., vanquishing skepticism about its prospects, was the top S&P 500 stock on news it signed up 2 million more US customers. The DVD and online video service’s gain of 134 percent in 2013 is the best on the S&P 500. Netflix is now the leader in online video, recovering momentum after pricing missteps two years ago. Quarterly profit was $2.69 million, versus a $4.6 million loss a year earlier. Sales rose 18 percent to $1.02 billion.