Have we reached peak Netflix (NFLX) - Get Report ?

Between trade war tensions that rocked the overall markets, Disney moving closer to acquiring Fox's assets for its own streaming service  and looming threats from Amazon (AMZN) - Get Report  and Apple (AAPL) - Get Report , the streaming powerhouse hasn't had the smoothest week.

After plunging 6.5% on Monday to $384.48 -- its worst percentage decline in two years -- Netflix's stock had popped back up to $395 by Thursday close. But some investors are giving its sky-high valuation a second look. Netflix currently trades at a lavish 104 times next year's expected earnings, according to FactSet.

"The question we have been asked most by investors lately is: 'what do you put in your numbers to justify the stock price?'" wrote Macquarie's Tim Nollen in a note Thursday in which he raised his price target for Netflix to $430. 

Bullish analysts like Nollen point to Netflix's global expansion -- it reported 5.46 million new subscribers outside of the U.S. at the end of Q1, bringing its international total to 68.3 million -- as evidence that the streaming giant will soar even higher. In his note on Thursday, Nollen predicted that international subs will crack 200 million by 2023.

But there could be speed bumps ahead.

Netflix's competitors are on the attack. Newly cleared to acquire Fox, Disney is planning its own streaming service for 2019 and prepping for an aggressive launch. 'Disneyflix' will serve up video from a number of popular properties, including Marvel, Lucasfilm and Pixar and Disney, and the company is placing its marketing chief in charge of promoting the service.

Apple is in the mix, too, reportedly building an ambitious streaming bundle that goes beyond just video. According to The Information, Apple's forthcoming service will weave together exclusive video -- it just inked a multi-year deal with Oprah to create original shows -- as well as music and magazine articles.

At an event on Monday, Apple CEO Tim Cook didn't discuss the bundled service but hinted at the company's holistic approach to original content: "We're going to have different people writing exclusively for this. So I'm really optimistic we can make a contribution here," Cook said of Apple News, which is also getting an overhaul in the forthcoming iOS12.

"Apple is a formidable competitor with deep pockets," Needham's Laura Martin told TheStreet, adding that Apple's existing music subscribers could give them a head start. "If I'm already an Apple Music subscriber, I'm more likely to use this video product."

Another number that worries some investors is Netflix's debt. It spent $8 billion on content in 2017, and finances some of that burn by selling debt, having raised $1.9 billion in debt in April, its largest-ever round of fundraising. It currently has billions in content spending commitments, including for 80 original films and hundreds of new shows. 

"Netflix should be selling equity, not debt, at these valuation levels," Martin added.

Netflix CEO Reed Hastings told investors in July 2017 that blowing cash was "an indicator of enormous success," but they're beginning to pull back spending a tad, spending less per new subscriber over time according to a recent analysis. At the same time, as deep-pocketed tech firms compete for media deals, the costs of acquiring good content could float higher for everyone down the road -- Netflix included.

"If their subscriber growth ever went materially negative, without a price increase, their results could be overwhelmed by their significant fixed costs," wrote Pivotal's Jeffrey Wlodarczak in a note last week. 

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