Mark Spiegel, founder of hedge fund Stanphyl Capital Partners, says the Model 3—which Tesla CEO Elon Musk has promised to sell for as little as $35,000—may put Tesla on a path to bankruptcy before it even comes out.

Speaking at the Robin Hood Investors Conference this week, Spiegel laid out his case in a 152-slide presentation on why he is shorting, i.e. betting against, Tesla stock. Factor in the debt, and he thinks the car company is worth less than zero. “I continue to believe that it’s the market’s biggest single-company stock bubble,” Spiegel elaborated in his November letter to investors, obtained by Fortune.

That so-called bubble deflated a bit after Spiegel’s presentation Tuesday morning, with Tesla stock falling more than 3% by the end of the day, while the broader market rose. Tesla shares fell another 4% Thursday after Spiegel’s presentation from the conference (which was closed to the media) was shared publicly.

Spiegel’s Stanphyl Capital manages $9 million. While that’s tiny in comparison to other hedge funds whose managers also presented at Robin Hood, from Jeff Smith’s Starboard Value to David Einhorn’s Greenlight Capital, Stanphyl’s assets have quintupled since Spiegel launched the fund about five years ago. This year, the fund has returned nearly 35% through November.

It isn’t the first time that a hedge fund short-seller has publicly attacked Tesla recently. Jim Chanos, the Kynikos Associates investor who lucratively shorted Enron before its scandalous demise, said in September that he is also shorting Tesla, believing the company is doomed, particularly after its controversial merger with SolarCity (SCTY) is completed. Tesla’s stock price is down about 25% in 2016 so far.

But while other Tesla critics have emphasized the company’s rapid cash bleed; recent controversy over crashes seemingly related to drivers’ use of its autopilot feature; and conflicts of interest with SolarCity, of which Musk is chairman and his cousin is CEO, Spiegel focused on a different problem for Tesla.

The prospect of a $35,000 “mass-market” Tesla Model 3—much more affordable compared to Tesla’s other vehicles, which cost at least twice as much—is the “real reason” investors have bought into Tesla’s stock, Spiegel said at the conference Tuesday. But “that will never happen,” asserts Spiegel. That’s because at that price Tesla would be selling the Model 3 at “a gigantic loss”—indeed, it could lose nearly as much on each car as the price customers are paying for it, Spiegel estimates.

Here’s how he got there, by the numbers:

• In Tesla’s latest quarter, it reported a $22 million surprise profit, its first in years. But much of the boost came from a one-off sale of government subsidy credits for electric vehicles that Tesla had been collecting. Without that, the company actually lost $117 million in the third quarter—or a loss of $4,710 per car.
• Each car Tesla currently sells costs $81,000 to build, Spiegel estimates. Those cars are currently profitable on their own (excluding leased cars and other unrelated company expenses)—but they sell at an average of $105,900, a price point that’s only affordable for a higher-income segment of consumers.
• In order to sell the Model 3 at as low a price as $35,000 and still make a profit, Tesla would have to cut its production costs by more than half.
• Where will Tesla find all those savings? The company hasn’t said specifically, but Spiegel estimates that it can cut about $6,000 off the $81,000-per-car cost by using its new batteries produced at its so-called gigafactory (which also cost $5 billion to build), another $5,000 by using cheaper parts for the Model 3—substituting steel for aluminum, for example—and $5,000 on top of that by finding ways to make its manufacturing more efficient (perhaps with greater automation). Still, that only brings the cost to build each Model 3 down to $65,000, much more than Tesla plans to sell it for. But Spiegel gives Musk some benefit of the doubt, and allows for what the investor calls a “cost savings fudge factor” that’s “extremely generous” and “probably undeserved” but which could knock off as much as $15,000 or so off the cost—bringing the cost per Model 3 down to just under $50,000, say $48,000 at the lowest.
• While Tesla has said the Model 3 will be available for as little as $35,000, Musk has predicted that the average sales price of the car will be $43,000, once customers add various upgrades and features. At that price and a minimum of $48,000 in costs per car, Tesla would lose at least $5,000 for every Model 3 it sells.

The obvious solution? Tesla needs to raise the price of the Model 3—to at least $50,000 for a bare-bones model, or 43% higher than the price currently promised, Spiegel predicts. “I wouldn’t be surprised if Musk claims a $35,000 base price but then never delivers any even CLOSE to that number,” Spiegel tells Fortune in an email.

It wouldn’t be the first time Tesla hiked the base price of one of its cars after promising it would be lower. When Tesla began delivering initial orders of its Model S electric sedan in June 2012, it sold them at a base price of $57,400. Just five months later, however, Tesla raised the car’s starting price to $59,900. About four months after that, though, Tesla cancelled the lowest-end Model S version, making the car’s new starting price $10,000 higher, at $69,000—20% higher than the low price it initially teased.

Yet with the “mass-market” Model 3, selling the car for more could be just as fatal a sentence for Tesla as selling it at a loss. If Tesla raised the base price of the car to $50,000 or more, as Spiegel expects, the Model 3 would no longer be competitive with the many other electric cars that will be on the market by then—as the Model 3 won’t start shipping to customers until the end of next year, and likely not before the end of 2018 for most orders, analysts predict.

For example, at a price of $50,000, the Model 3 would be about 33% more expensive than the cheapest Chevy Bolt, an electric car from GM (GM) that’s already on the market starting at $37,495 at select dealerships—more than a year (or two) earlier than the Model 3.

And the higher the price of the Model 3 goes, the more Musk’s dream of a cheap and affordable Tesla disappears. And without that mainstream demand, Spiegel thinks Tesla’s future doesn’t look so bright at all.

Tesla did not immediately respond to a request for comment.