As of this week, Hulu's major stakeholders have all reported earnings for the most recent quarter — and all three posted some big losses for the streaming service as it ramps up investments.

Hulu doesn't report official numbers — and declined to comment for this story — but some rough math of write-downs by Comcast, Disney and Twenty-First Century Fox puts Hulu's annual losses in the neighborhood of $1.5 billion. Each company owns 30 percent of Hulu.

Comcast, which also owns CNBC-parent NBCUniversal, and Fox both attributed losses to Hulu that had doubled from the year-ago quarter. Comcast posted a $107 million loss from Hulu and Fox posted a $127 million loss.

Four quarters of losses that size, accounting for the companies' shares, puts annual losses for Hulu between $1.3 billion and $1.6 billion. Research firm BTIG in February estimated Hulu's 2017 losses at under $1 billion.

Disney, the only company of the three not to break out losses for Hulu, noted repeatedly in its earnings release and on the company's earnings call that financials dipped for the fiscal third quarter in part due to "higher losses from Hulu."

And yet, Disney is about to double its stake in Hulu once it closes its proposed acquisition of Fox. A representative for the company wasn't immediately available to comment for this story.

If anything, the willingness to take on double the losses is credit to Disney's ambitions in streaming and over-the-top, direct-to-consumer content.

The company last year announced plans to launch an in-house streaming service to compete with industry leader Netflix. But the company has said it'll be at least another a year before launch, and drawing eyes from incumbents will take time.

"[CEO Bob] Iger seems committed to Hulu," Argus Research Analyst Joe Bonner said in an email to CNBC. "As he should be since it's an OTT streaming platform that is already up and running, rather than the prospective one that management is currently promising for the end of next year and even if delivered on time will take years to build a subscriber base."

Hulu executives have warned shareholders of growing losses as the company invests in building a subscriber base to rival Netflix's. In May, the company announced it had surpassed 20 million American subscribers, having added 3 million subscribers since January.

Netflix, for comparison, reported 57 million U.S. subscribers for the last quarter, an increase of fewer than 1 million subscribers over the three-month period.

"Investing in Hulu right now is probably money well spent and should not significantly impair [Disney's] balance sheet," Bonner said.

Disclosure: Comcast is the owner of NBCUniversal, parent company of CNBC and CNBC.com. Comcast is also a co-owner of Hulu.