LOS ANGELES — Netflix slashed its prediction for how many US video-streaming subscribers it would add this year after subpar third-quarter results, causing a sharp sell-off in its stock in after-hours trading.
The Los Gatos, Calif.-based company said it added 1.2 million net streaming subscribers in the United States in the three months through September, which was on the low end of its forecast.
The disappointing figure caused Netflix to cut its estimate for full-year US streaming subscriber additions to between 4.7 million and 5.4 million. Previously, Netflix predicted it would gain as many as 7 million domestic streaming subscribers.
Growing streaming subscribers in the United States is crucial to Netflix because the number of DVD-by-mail subscribers continues to fall and its losses internationally are mounting. Netflix also needs more subscribers because it is sticking to its price of $8-a-month for unlimited video streaming.
CEO Reed Hastings brushed off the subscriber miss, even as Netflix shares fell $11.13, or 16.3 percent, to $57.09 in after-hours trading.
‘‘In perfect hindsight, it was not the best choice to put out that high a goal,’’ he said in an interview with the Associated Press.