Reed Hastings NetflixReed Hastings, co-founder and CEO of NetflixREUTERS/Mike Blake

Netflix crushed its Q4 earnings on Wednesday, sending its stock soaring, but there’s one thing Wall Street is still worried about: how much cash the company is burning.

Netflix is set to have a negative free cash flow of $2 billion in 2017, versus $1.7 billion in 2016.

The reason, according to Netflix, is that actually making shows yourself costs a lot of money up front.

Netflix is confident it will make that money back over the long run, but it does provide “some lumpiness in [Netflix’s] working capital needs,” according to its Q4 letter to shareholders.

For a fuller explanation, however, it’s good to go back to Netflix’s Q3 letter to shareholders, where the company lays out the case for the continued escalation of its cash burn.

Here’s what Netflix said in its Q3 letter:

The increase in our free cash flow deficit reflects the growth of original content, which we are increasingly producing and owning (rather than licensing). Self-produced shows like Stranger Things require more cash upfront as we incur spending during the creation of each show prior to its completion and release. In comparison, we generally pay on delivery for licensed originals like Orange is the New Black and we pay over the term of the agreement for licensed non-originals (eg, Scandal).

Over the long run, we believe self-producing is less expensive (including cost of capital) than licensing a series or film, as we work directly with the creative community and eliminate additional overhead and fees. In addition, we own the underlying intellectual property, providing us with global rights and more business and creative control. Combined with the success of our portfolio of originals and the positive impact on our member and revenue growth, we believe this is a wise investment that creates long term value. Consequently, we plan on investing more, which will continue to weigh on free cash flow.

Instinet Nomura analyst Anthony DiClemente called the cash burn his “lone concern” about Netflix’s business, in a note distributed Thursday. However, he also wrote that Netflix’s “long-term margin expansion trajectory is better than we’d thought,” and remained bullish long-term.

That said, don’t expect Netflix’s cash burn to go away any time soon, according to Macquarie’s Tim Nollen, who wrote that Netflix’s 2017 deficit “may not be the worst of it.”

“Netflix intends to expand to over 1,000 hours of original content this year and most likely more again next,” Nollen wrote in a note distributed Thursday. “But again,” he continued, “content investment drives the [subscriber] growth, and for now this is what matters most.”

In October, Netflix announced it was raising another $800 million in debt, bringing its total long-term debt to over $3 billion.

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