Netflix Inc (NFLX.O) crushed Wall Street forecasts by adding 5.2 million new streaming customers in the second quarter and predicted continued momentum as it expands around the world, lifting its stock nearly 11 per cent on Monday.

Shares of the company that pioneered streaming television jumped to US$179.16 in after-hours trading, beating their all-time intraday high of US$166.87 on June 8.

Netflix expects foreign growth to lead to its first full-year profit for overseas markets in 2017, the company said in a letter to shareholders.

At the end of June, Netflix for the first time recorded more subscribers abroad than in the United States — 52.03 million versus 51.92 million.

The company said a strong slate of content, such as "13 Reasons Why" and the latest season of hit political drama "House of Cards," helped attract new customers in the second quarter, which is typically its slowest season of the year.

Netflix added 4.14 million non-U.S. subscribers, compared with the average analyst estimate of 2.59 million, according to data from analytics firm FactSet.

In the United States, it signed up 1.07 million subscribers, beating analysts' average estimate of 631,000.

Netflix is expecting international subscriber additions of 3.65 million for the current quarter, compared with analysts' average estimate of 3.2 million.

The guidance assumes much of this momentum will continue, the letter said, though it added that Netflix's forecasts had been too optimistic at times.

Netflix is spending US$6 billion a year on content to win new subscribers in a quest to become the dominant movie and TV streaming service around the world even as it faces a slowdown in U.S. customer growth. It is customizing content for different countries and adding shows in various languages.

The Los Gatos, California-based company said it expected to report negative free cash flow "for many years" as it invests in content to add new subscribers.

Netflix said revenue rose 32.3 per cent to US$2.79 billion in the quarter.

The company's net income rose to US$65.6 million, or 15 cents US per share, in the latest quarter from US$40.8 million, or nine cents US per share, a year earlier.