Elon Musk has said Tesla so high, but he doesn’t have to think about it any longer. The automaker is no longer the most valuable car company in the U.S. after a disastrous week on Wall Street that brought its shares down a 15 percent, due in part to that it has experienced a “severe” shortfall in production of 100-kWh battery packs.

By midday today, Tesla’s shares were down 3.7 percent, according to , which brought the automaker’s market cap to $51.8 billion. General Motors retook the no. 1 slot for the U.S., the Times said, with a valuation of $52.7 billion.

While it may be no surprise to Musk, it’s quite the turnaround for Tesla. Over the course of a year, its stock price has jumped exponentially, thanks to growing expectations for the imminent release of the all-electric Model 3 sedan, and Tesla’s incredibly ambitious goal to produce 500,000 vehicles by the end of 2018.

So, what happened? The slide began earlier in the week, when Musk disclosed that Tesla will start —a surprise for the company—but on a timeline that fell far-short of promises made by the automaker a year ago. In 2016, Tesla said it aimed to produce 100,000-200,000 Model 3s by end of this year; instead, , it’ll produce somewhere between 20,000-25,000.

The following day, Tesla released Q2 sales figures, which revealed . That compelled some bearish analysts to suggest that demand has plateaued for Tesla’s Model S sedan and Model X sport utility car.

“Tesla’s Q2 production and deliveries report raised more questions than answers, particularly about Model S and X demand,” Toni Sacconaghi, a Sanford C. Bernstein analyst, wrote in a report Wednesday that was . “The Tesla investment thesis hinges on the success of Model 3, and the ability for the company to ramp production, make the car profitably and deliver good initial build quality.”

With Musk the Model 3—the company’s way of trying to ensure sales of the Model S and X remain consistent—it’s clear that Tesla agrees that high demand of its more-expensive vehicles is imperative for its future success.

According to Tesla, the sales figure issue stems from a “severe production shortfall” of 100 kWh battery packs.

“The technology challenge grows exponentially with energy density. Until early June, production averaged about 40% below demand,” . “Once this was resolved, June orders and deliveries were strong, ranking as one of the best in Tesla history.”

That failed to stem the tide of skepticism that creeped in from Wall Street, culminating in an analysis from Goldman Sachs, which predicted that Tesla’s , and the subsequent drop on Thursday to no. 2 of the most valuable U.S. carmakers.

Things could change on a dime, of course. Who knows, maybe Tesla will hit that (new) goal from Musk of producing 20,000 Model 3s in December.