Online movie renters Netflix saw its shares tumble nearly 10 percent to $21.70 Wednesday after saying that it expects to end up with about 7.3 million subscribers by the end of the year, 13 percent fewer than it had forecast in January. Shares in the company have fallen 26 percent over the past year. Netflix apparently was hit hard by a rival service from Blockbuster that allows customers to receive movies in the mail, then exchange them in Blockbuster stores. Reporting on Netflix's woes, today's (Thursday) Los Angeles Times commented that Blockbuster "is finally getting some payback in its battle with rival Netflix."